On my 88 F150 I have this problem. If I speed up fast it is like the engine has absolutely nothing to give. Now if I speed up slow it seems to drive just fine. When it idles it does have a good shake to it. It has an AOD trans and a brand new exhaust system from the heads back. I have been chasing the problem for a while now with no success. I have rerouted the pcv vaccuum too. I did that a few months back. I had done a trans service on it and after a few days of doing this then the problem hit. It was driving just fine after the service. The shake has been there for a while, about 2-3 months or so. Any thoughts???

 

Also, I did notice tonight that it starts doing this at around normal operating temp. Maybe this helps a little.

 

Have you pulled the codes?

 

I just got done pulling the codes and here is what I have found. On the KOEO test I got a code 32 for the EGR sensor. I get that one about once every three months or so. My EGR valve went bad and I replaced it with one from NAPA and decided to put in a sensor while I was right there. I have had this one happen after I replaced it and replaced the sensor again. That did not solve it so I then replaced the valve too. That took care of that last time I had that one. I think that one I will have no problem solving. On the KOER test I got a code 32, (same as before) and I got a code 44 for a vacuum problem. That one I think that I may have some trouble with because I have never had to deal with that one before. This is what it says in my Haynes manual - Secondary air inoperative - perform pump, valve, valve vacuum, and solenoid checks. Where would I even begin with this?

 

That's the air pump system, which has a couple of vacuum controlled valves in it. One is close to the air pump, the other one is at the back of the engine. The vacuum to the valves is controlled by a couple of solenoid valves at the left rear of the engine on the same bracket as the ignition coil. The resistance across the solenoid terminals should be 51 to 108 ohms. The valves should be checked for holding vacuum with the engine off. Also check vacuum lines from the intake manifold to the solenoid valves and from the solenoid valves to the air valves. Check the air valves for vacuum leaks and for redirecting the air when vacuum is applied and removed. Also make sure the pump is pumping air. One last thing, there are two check valves, one where the air line connects to the crossover tube between the heads at the rear of the engine and one where the air tube connects to the metal tube to the catalytic converter. Make sure those work, so exhaust doesn't back up into the air system.
This all assumes yours is similar to my 89. Good luck.

 

Thanks for all the info. I have never messed with any of that before, but it looks like tomorrow I will be diving into it. Thanks again, I will post what I find out.

 

Well I checked the air pump, that works. I performed a ohm check on the EVR solenoid and it checked ok. Those were the only things that I could really check without having a hand-held vacuum pump. I think that I may just start replacing the solenoids and go from there. One of the two other solenoids was closed and the other was open. From what I have read, they are supposed to closed normally. I am going to start there. Anything else you think that I am forgetting, besides the check valves?

 

I bet the open solenoid is what's causing that code 44.

 

See, that is what I was thinking. I work for NAPA and I know that we can get a few of those so I am going to dig through the books tomorrow and see what I can find. Thanks for all the help.

 

Well after replacing just about everything behind the air pump I am still getting a code 44 - AIR system inoperative right side. Now here is what I have found. I replaced the air bypass valve right behind the air pump, the air diverter valve behind the engine, the check valve on top of the emissions pipe as well as the the emmisions pipe itself (the one that runs between both heads). The check valve that was inbetween the the air diverter and the cat has been removed as well as the cat has been taken out. The air diverter had a bunch of build up in it as well as the check valve on the the emmisions pipe and the pipe itself. After all this the truck runs considerably better now. It idles better now and does not really fall on its face after it goes closed loop. The air pump still appeared to be working although it does seem like it is making some noise. I plan on checking that out tonight as well as the canister too. I still have the code 44 as well as a code 31 for the EVP sensor too low. This is a Ford calibrated one too and it still says this. The EGR valve is brand new. I am pulling my hair out trying to figure this out, anyone have any ideas at all?!?!?!?

 

As to the EGR, maybe this thread will help: https://www.ford-trucks.com/forums/s...32#post1610732

 

Thanks for that link. It was actually quite informative. I should also say that I replaced all the solenoids too and I still get the code. This is quite confusing.