He said in post #1 that the IAC has been replaced.

 

Well I've been driving back and forth to work all week. Looks like 90 miles since the weekend. I still haven't gotten a CEL. It seems to be running a little better, but sometimes you can still feel the up and down idle. Especially when going in reverse. Last thing we did to it was on the weekend. We removed the throttle body cleaned it and put new gaskets. I also changed TPS sensor since it was on the back. Today I just got the front O2 sensor and a new Motorcraft PCV valve. I've got the rear O2 sensor coming as well. I'll try and get this stuff on this weekend. I can feel a slight drop in power too like something is holding it back. It's not dramatic but it's not something I noticed before all the EGR codes. I'm really starting to wonder if the MAF was bad for so long it took out the catalytic converter. Because I can hear inside rattling around but I've got no codes and no heat differences in and out. I'm also still waiting on the vacuum gauge I ordered. As far as the oil separator box. You do have to remove the lower intake to remove it. Then when you get it off I'm not sure you can still get the o-ring or gasket to go with it. I'm not sure whether there is any kind of gasket or o-ring for it. I tried to remove one in the salvage yard but I didn't feel like removing the lower intake. If I was going to go to all that trouble I would want to make sure I've got whatever gasket I'll need for the oil separator box, clean the injectors, replace the intake cooling hose, change the plugs and wire on that side. I've taken off the upper intake before to do the tune up but never the lower. I have changed the fuel injectors a couple years ago but didn't have to remove the lower intake.

 

Another update. I replaced the arcing front coil now. So both coils have been replaced. However, it didn't change the way the truck ran at all. Also the P0171 has come back on and has not gone away in 100s of miles of driving. So there is still something very wrong. I've already checked the fuel pressure at idle, and in all gears and it's 65PSI. We could only get to the #1 and #2 fuel injector with a NOID light and they were working. We listened to all the fuel injectors with a probe and they all sounded the same. So it's either losing air or not getting enough fuel. But shouldn't fuel be out of the question as long as the pump is operating at the right pressure? I cannot find any vacuum leaks. It seems that the idle rolls a lot when it's first started for the day and put into reverse. Then as you drive it and stop somewhere and restart it. It does the same thing. Driving is ok but stopping and slowing down it even shuts off sometimes. I can't see any PID values off the charts. I will watch the fuel trim today when I drive to work. When I had it scanned by a mechanic a few days ago he showed me that the #2 cylinder was all over the place. I pulled the plugs on both sides and they looked normal. It's almost time to take it to Ford.

 

Ok, good feedback on the fuel pressure reading & replacing the coil pack again. Was it the primary coil pack & was it arcing at the #2 plug wire connection on the coil pack?

What did the tech find that was "all over the place", while monitoring #2 cylinder?

 

I don't think it was the #2. It was the front coil pack. I replaced the rear on Monday because it was arcing in numerous places. Replacing them had no affect at all on the stumbling idle and internment shut offs. The mechanic did a cylinder balance test on his snap on scanner. He said #2 value was all over and said it was misfiring. When I pulled the #2 plugs they were normal light gray deposits for around 20000-30000 that they've been in there. Driving to work I monitored short and long fuel trim. Driving they were both well below 20 but mainly the short term jumped to 20-30+ reading when stopped at lights and when I pulled in the parking lot and put it in park. If I rev it in park the short term goes where it should well below 20. But sometimes both short and long term were high. If I stop and get out for a few minutes then get back in and start it really runs rough until I get going. Usually sitting long periods or overnight the first start it idles normal.

 

Ok, when you stand in front of the vehicle & look at the front coil pack, was it the left front, left rear, right front, or right rear tower area that had electrical break down.

On the fuel trim, are those +/positive, or -/negative numbers?
If positive, it means the computer is having to add that much fuel to correct for too much air & if they are negative numbers, then it means it's having to take away that percentage fuel, to correct for a over fueling condition.

 

What do your ELM snapshot PID's look like when the vehicle runs rough & stalls when coming to a stop?

 

If the power balance test was showing the rpm drop was "all over the place" when the scan tool disabled the #2 cyl fuel injector, then it suggests you need to perform a compression test on #2 cyl. It kinda sounds like you may have some kind of a valve problem. Just guessing, maybe a overhead cam lobe, or maybe a valve stem, or valve seat problem.
Since he said #2 cyl was missing, something seems to be going on with it.

 

I didn't have the elm hooked just my hf scanner. The #s were all +. When I saw the arc on the front coil it looked as if it were the right front most coil tower. I'm not sure what value was showing when he did the cylinder balance test but it didn't look like rpms. He seemed to know it was #2 missing right away. When I had the elm scanner hooked a week ago after getting home I just compared them to the fsm chart and all were within range. I don't think I had the fuel trim running that time. He told me to do a compression test but I noticed I don't have my tester anymore. So if the fuel trim is high + does that mean too much air?

 

Ok the right front coil pack position is for the drivers side #3 spark plug.

For the record:
The front/radiator side coil pack is for the drivers side spark plugs.
The right front position of the front coil pack is for the drivers side #3 spark plug.
The right rear of the front coil pack is for the drivers side #2 spark plug.
The left front is for the drivers side #1 spark plug.
The left rear is for the drivers side #4 spark plug.

The rear/firewall side coil pack, is for the passenger side spark plugs.
The right front position of the firewall coil pack is for the passenger side #4 spark plug.
The right rear or the firewall coil pack is for the passenger side #1 spark plug.
The left front of the firewall coil pack is for the passenger side #2 spark plug.
The left rear of the firewall coil pack is for the #3 passenger side spark plug.

Since you say you've used the most inexpensive plug wires, they also belong on your suspect list, as they're worked Twice as hard in our waste spark ignition system, that fires it's plugs on Every rotation of the crank shaft.
From end to end, All plug wiring should measure 1000 ohms/inch of length, 30,000 ohms max, no matter the length.

All wires should be routed Exactly as the factory had them, using all wire looms & stand-offs, to prevent high voltage induced cross firing.

The insides of the plug wire boots should have a light coating of silicone grease, as should the spark plugs external ceramic insulator, to prevent corona on wet dewy morning starts, or damp rainy days.

Call the Tech & find out what parameter was jumping around all over the place when he was performing the power balance test, that info is important.
Most times the scan tool disables a fuel injector & measures the rpm drop, to spot a suspect cylinder. So if compression on #2 cylinder was all over the place, say from valves not sealing right from something like CCDF = Combustion Chamber Deposit Flaking, holding the exhaust valve open, it could cause your intermittent rough running engine at idle, or when coming to a stop.

Yes a + fuel trim indicates the computer is having to add fuel because the upstream O2 sensor is measuring too much air/O2 in the exhaust.
Typically that could come from a vacuum leak, that could also come from a faulty sticking open, or worn out PCV valve, or a leak in it's rubber hoses or fittings.
As it's down stream of & it's calculated for vacuum leak is not being monitored by the MAF sensor, so if the PCV system isn't working as designed, it can corrupt fuel trim lean & cause the upstream O2 sensor to report a lean mixture & that will have the computer to have the injectors add fuel, so the fuel trim would go + = adding fuel.

Keep looking I think your about to find the culprit.

 

I can check with the mechanic to see what the balance test was reading. It was warm 60s this afternoon and on the way home it was in the 40s I noticed the long term trim was in the +20s. I can believe the pcv system could be an issue but it's hard to service. The only way to get off the pcv separator is remove the power steering bracket and whole intake. The separator isn't available anymore and not sure you can even get the new gasket to take it off for cleaning. The pcv valve itself is rattling when you shake it and no sludge on the bottom. I believe you can still get the pcv hose and crankcase breather hose. How can we test the pcv system? If there were valve sealing problems wouldn't you expect fouled out plugs? It ran as it should all the way home tonight a 15 mile trip with heater on.

 

When last was the PCV valve changed?

 

Plugs, wires, coil packs, air filter, and pcv were all done also about 30000 miles ago. Of course I just changed coil packs again this week. I've never changed the pcv hose or took out the pcv box to clean. I've changed the valve cover breather hose once before.

 

If this is the vehicle in your profile that has over 250K on it, that PCV vlave & it's rubber connections have lived 2.5 lifetimes, so at least the PCV valve is well past time for replacement & the rubber hoses are known to dry rot & leak.

 

I noticed something when reviewing the FSM PID values under Generic OBDII PID values. It lists the MAF in G/S which is what I was viewing on my HF scanner while driving. I had Short term, Long term, RPM, and MAF recording. I noticed when the truck was around 2000-25000 RPM the MAF was in the 30s. According to the Generic OBD II values it should be at a maximum of 10.7 at 2500 RPM. The PID Chart from the FSM shows the MAF V PID which I haven't checked lately. The MAF was replaced like last month. I bought a Walker unit off of Rockauto. I still have the old one because there was no core. Should the MAF value ever be that high, because I was driving, so the air was moving in through the filter box. Maybe the chat in FSM is meant for it at an idle, not moving. Any ideas?