Grand Prix is hesitating during acceleration

[BNaylor]

I agree with Rich.

Plus you can test the fuel pressure regulator to see if it is regulating properly and also pull the vacuum hose going to the throttle body and check for possible raw fuel due to a ruptured diaphragm which is possible but not that common.

I would go with a CAT converter since if defective the internal CAT temperatures can rise dramatically and the effect may be seen when the EGR is called active by the PCM and hot exhaust gases (more than normal) are injected back into the UIM.

[Sunspot]

Had GM warranty the CAT, we are at 118,000 and the warranty went to 120,000, no arguements from them on if it was covered or not. Anyway the CAT replacement did the trick on the loss of power and hopefully it was completely responsible for the hole burned through the plenum, might change that FPR anyway just to be safe. Thanks for all the input.

[richtazz]

You're welcome sunspot, and thank you for the feedback. Letting us know your problem was resolved may help someone else reading this thread with the same problem.