I thought 93 on up used 3 digit codes. I might be wrong though.

 

Vacuum seems to be good. It runs 17in at idle in park. Drops down to 14in in drive or reverse. Gunning it in park brings the vacuum up to 22in then drops down to 14in upon decel then goes back to a rock solid 17 in.
I wonder if it could be a crappy battery? It's still running lean and smokes grey.

 

Vacum gauge can be a very useful tool.
Read this info to learn how.
How to Use and Interpret a Vacuum Gauge
Good luck Frank

 

Thanks fmr9! I looked at that and ascertained that the vacuum showed that the engine is basically in good shape. I went ahead and changed the O2 sensor since I already had it and it seemed to help the lean tailpipe smoke after bit was changed. The engine seems to vibrate when I accelerate or decelerate like something is holding it back.
I just returned from Iraq a month ago and I'll start back working at my civilian job tomorrow. I'll drive it tomorrow 18mi 'round trip and see if the fuel injection cleaner will have an effect over time. If not I will probably go ahead and change the sparkplug wires.
I'll be changing the clockspring this weekend anyway. FWIW does anyone know what size bolt holds the steering wheel on the column?

 

Believe it or not, I'm still having problems but I've changed nearly every sensor imaginable.Timing is at 10 deg both with and without spout conn. connected.
Anyhoo I am getting 2 codes:
331-?
542- fuel pump secondary circuit failure. PCM to ground.

In a search I read that the 331 code may be linked to a bad EGR valve relay. EGR sensor and valve have both been changed.

Basically I have to give the truck some gas either by pumping the acc first or lightly pressing the throttle during startup. I have to accelerate the engine or it will die. If it's warmed up the engine might keep running although at a very low RPM. I can put it in gear and sometimes it will stay running with my foot off the accelerator. I have attempted a drive around the block and it dies when stopping.

Vacuum holding the engine at an acceptable idle speed is rock solid 17psi. When accerating it drops to like 2psi and back up to a steady 15psi except with a miss that makes the vacuum stutter every few seconds.

Could the PCM be bad?

I have replaced:

Cap
rotor
spark plugs
fuel filter
serpentine belt
O2 sensor
TPS
EGR valve and sensor.
Coil
ignition switch
alternator
battery
MAF sensor
air filter
fuel regulator
PCV valve
injectors cleaned

What would you do next?

 

Sounds like you are getting the truck in good shape, and getting very well acquainted with the truck. I went thru a similar process when I got mine, but Buff never did run real bad, he just had a slow rough idle, and sucked gas like crazy. I did a lot of the work you have done, and he seemed to run a little better with every change. Never did significantly effect the gas mileage.
There are sensors that may or may not affect your problem. there are two temperature sensors on the engine. One is a single wire sensor and is for the temp gauge on the dash. The other is a two wire sensor and is used by the computer to determine when the engine is fully up to temp, and adjust the mixture. The original thermostat was 195 deg, and this is what the computer is looking for. Your thermostat may be not working properly, or it may have been replaced with a lower temp setting. If the thermostat is not working correctly, or the sensor is not reporting correctly, the computer does not adjust the mixture for a hot engine.
When I replaced the injectors, I also replaced the air charge sensor while I had the upper intake off. This sensor was not throwing a code, but the appearance when compared to a new one was dramatically different. The old one had so much buildup on the sensor tip, it would barely come out of the hole. Buff ran better and seemed more powerful after this work, but the injectors were changed at the same time, so it is hard to say how much was a result of the sensor change.
I also pulled and cleaned the Idle Air Control, IAC, early in the process, and a couple weeks later replaced it. That helped a little.

One thing you reported, doesn't sound right to me. I am sure your timing would be much different with the spout connector instaled. If the timing is the same with and without the spout in, something is not right at all.
I hope you figure your problem out.
Good Luck Frank

 

Well, fmr9 I think it's fixed. I replaced the IAC and the idle came up where it needed to be. After a little drive I decided to check the timing again and it was off. I timed it and it runs almost like new now. The gunk that was in the old IAC was horrible.I sprayed some carbuerator cleaner down the intake holes before I put the new IAC on. When I changed the TPS I had the throttle body off and noticed the IAC but wasn't sure what it was or what to call it. With all the new parts I basically have a new 146000 mile truck (almost). I was running out of things to change on it! Thanks for giving me an idea of where next to look on it and saving me at least $239.00 if I had tried a new ECM. I hope anyone else having these kinds of problems check your IAC. Some parts I replaced maybe didn't need replacing, but I at least have peace of mind that they are new.
Thanks again! Now I can drive my truck to work and not that mean ol' Mustang!