Hey everyone, long time lurker, first time poster here. I buy and sell cars, have been for years and worked on my fair share of new and old GM products. Earlier Today i purchased a 2003 Grand Prix GTP from a recently widowed friend of mine. Knew nothing about the car been sitting for about a year. $300.
Formalities out of the way, I got it started up and it idles on it own will not rev past 1.8k-2k and causes horrible shaking.
In gear the car can barely pull itself in to the driveway. I've checked all the normal stuff, plugs, wires, injectors, MAF, vacuum leaks, etc. Everything checks out. I even disabled the injectors (with HPT) one-by-one to see if there's a problematic cylinder, no problems there.
The only DTC I've experienced is P0300 (random misfire of course). And the only abnormality I've noticed is highly fluctuating STFT, somwhere between -5 to -25 rapidly. O2 sensor seems to be responding appropriately.
Is there something I'm missing???
I'm about to head to the store and pick up some fuel system cleaner, maybe that'll help.
Thanks, Levi.
