You stated that when you unplug the vac line to the egr, it runs better. Try blocking the egr off completely with a thin piece of sheet metal. This will prevent any exhaust from entering the intake through the egr itself. It could be leaking from the pintle not sealing. Its been known to happen more than you think. The big spring inside the egr could be sticking and not letting the pintle seat and seal off exhaust that is being sucked into the intake. Any leak at the egr is gonna cause you a problem. If it's exhaust leaking into the intake, it'll stumble really bad.

 

I had to do that on a 5.0 once, I used a Penney

 

Sorry about the EGR. When I unplug the vac there is no difference, because from what I understand there should be very little to no vaccuum at the egr at idle? I've also tried blocking it right off with a plate, and it doesn't help at all. When I pulled the plugs earlier they seemed pretty dry to me not wet at all. I had drove it home then pulled the plugs before doing the compression test.

 

I wish I had a parts truck to pull parts off... I would just swap the EGR anyways. I took it apart and looked at it and everything moves freely nothing seems to be gummed up and sticking at all.

 

Does your truck have dual tanks?

If so do they both work?

 

Also are you sure your intake isnt leaking?

 

No just has the single rear tank.

 

Im wondering if your upper or lower plenum of your intake isnt leaking.

 

I haven't checked. Would that cause it to have to turn over 2 to 3 times before firing up? And hesitate like it does? If so I'll take it apart and put new gaskets in it tomorrow.

 

It very possibly could cause it would be letting more air into the combustion chambers making a lean fuel mixture.

 

Okay. I wonder if there's a way I can check the plenum for leaks before taking it apart to replace it? Gaskets are cheap anyways haha. Thanks for the input man, I'll keep you posted on what goes on here. I've been reading the computer can fail too, it's a remanufactured one that's in there now so I'm also wondering if it is going to kick the can. Noticed driving home tonight it had a rough idle until I gave it a little more throttle to pick er back up too.

 

Its no problem at all, use carb cleaner around the plenum and if it is leaking bad enough to make it run like that then itll rev up on its own.

Right now its a guessing game using commen sense and experience lol also when doing these gaskets, use rtv, I have and have never had a single problem.

 

When a computer fails it will run like total **** through all rpm bands and not want to start, if it starts at all

 

Okay, I'll go grab some carb cleaner tomorrow and fire it up and spray around it see if I can't find some leaks.

 

I'm also thinking it sounds like an intake/vacuum leak, especially in light of all the replacements.

I got tired of hunting vacuum leaks in my truck, so I just replaced all the lines with rubber hose. Took about 2-3 hours but not a bad job.