Pontiac Repair: 1991 Pontiac Grand Prix SE 3.1, fuel pressure gauge, intake manifold gasket

Question
Hi, I am having a problem with my Grand Prix. Car starts runs and then stalls. When it does start, I am unable to give it gas, it starts to bog down, then stall. If I just leave it idle, it is ok for a few minutes then it starts running real rough and then stalls. Also when I was able to rev up the motor, it bogged down at about 4000 rpms. I have changed the following things so far. Fuel pump, filter, regulator, crank sensor, complete tune-up, T.P.S., I.A.C, ignition module, EGR, O2 sensor, E.C.M. I also just did an intake manifold gasket (very bad oil leak). I am not sure where else to go with this, so any help would be greatly appreciated.

Answer
Hey Richard:

You could have a back pressure issue with the exhaust in this engine. If it bogs down and sounds like it's not breathing properly. Disconnect the front exhaust pipe which is part of the catalitic converter and drive it. You could have a lot of other issues This engine needs what is called an idle learn It's a long drawn out process to do it. It will cause idle stalling but not a Bog issue. You can do a google search for 3.1 liter Idle learn procedure. Make sure the throttle body is clean not carboned up before you do it and also disconnect the battery for at least 5 minutes before you do that. The other thing I would do is put a fuel pressure gauge on this and drive it and see what it's at when it bogs down. It may be lacking fuel volume/pressure. You can also be looking at wiring issues. A bad ground or power feed to the ecm can cause a ton of wierd issues being that this car is 17 years old I would take a look at that as well especially if you live in the rust belt. One last thing on the idle issue make sure this has the correct PCV valve not a "fits all" Good luck :}