fix for hesitation/stutter intermittently

Anyone here have an 04+ GP with Series III engine? I've got 106k on my 05 GT, and have this intermittent problem where i'll start the car, and go to drive it but it has no power and surges with light pedal input, and bogs down when you get on it. Turn the car off, restart, and it works fine. This happens like every 10th start, doesn't matter if its a cold or warm start. I've been digging around the net trying to find others with this issue, but it doesn't seem there are many cars of this vintage to get high miles on them yet. I've found a few reported issues and people blaming the transmission, PCM, traction control etc... but no exact fix.

I think I may have found the culprit though. I believe it is a problem with the "drive by wire" throttle system. Its as though the PCM is not getting the correct throttle info when this happens (no check engine lights though). Has anyone ever replaced their gas pedal assembly? Its basically the pedal attached to some sort of electronic potentiometer box and looks like an easy part to replace. I saw there was a TSB somewhere (not sure of the number) that stated a similiar issue and the dealer was to replace the gas pedal assembly or throttle body to fix. My gas pedal has always been rather stiff as well which leads me to believe it could be the source of the problem. Also sometimes it will start and it will take very little throttle input and the car flies, most of the time it drives with what i would call normal response and then sometimes i get the no power/stumble issue (kinda like when traction control turns on where it surges the engine). I've removed and cleaned my TB, and all sensors are clean as well.

Trouble is finding a gas pedal assembly for a drive by wire car (malibu, G6, grand prix) is not easy to do used. And then there is the issue of a junkyard car also having the same problem. I'd like to find one and disassemble the electronic component and see if it needs to be cleaned or if resistance can be measured from the input like a TPS. Anyone attempted this or is this a fools folley? I can't find one locally and they are $50+ on ebay used so its alot of out of pocket to test this hunch. I don't wanna take mine apart because its my daily driver. Let me know what you think, thanks!

I think someone else recently had this same exact issue you describe. Try a search of the forum. I am not sure if he ever got his problem resolved.

The ETC problem could also be in the throttle body...not doing as commanded.

I would clean the throttle body thoroughly before doing any serious stuff as the blade could be sticking and causing driveability issues (note this problem and solution is also in other GM carlines such as the GMT800 Tahoe/Yukon with the 5.3L V8 and also ETC)

If that doesn't work, then I think I'd invest in some used parts and some careful one-at-a-time swapping in the name of troubleshooting.

Have you checked out the catalytic convertor. I had the same problem and it was the catalytic covertor that was 90% plugged off.

It sounds like a stickey throttle plate on a electronic throttle body.
On a drive-by-wire system, you can't mussel a throttle plate open like a cable driven throttle body.

Caution - Don't move the throttle plate by hand, you might mess up the calibration on your electronic throttle plate.

See bad electronic throttle body cleaning www.automotiveforums.com/vbulletin/showthread.php?t=968873 (http://www.automotiveforums.com/vbulletin/showthread.php?t=968873)