Thread: 2002 Grand prix GTP

Just recently changed manifold gaskets, valve gaskets for leaking due to dexcool. While had it apart changed plugs and wires. No more leaking but car is running real sluggish. In Idle it surges between 1500 and 2500 rpm steady. Drove and appeared to drive fine but after getting warm downshifted to third on its own and was not always responsive to gas pedal. Checked all connections nothing appears incorrect. Recieved codes PO101 and PO120 reset and drove fine for a little while ( about 4 miles and same symptoms but no engine light.

Try clean your MAF sensor. I had similar problems, eventually led to my car not even starting. Use MAF cleaner or electrical contact cleaner. P0120 relates to the throttle position sensor. Could be that too.

i bet you got 2 of the plugs mixed up on the tb. i think the tps and maf have the same connector

ricroc2001- I have the same year and make of your vehicle(mine is a 40th anniversary) and I replaced almost every gasket and seal that I know of. My mechanic called it a "complete engine kit" but it contains the lower intake manifold gasket, the head gasket, the head bolts, etc...With the labor it cost me a pretty penny, however a week later the engine light came on, and on idle the rpm would fluctuate between 1000-2000 randomly. I got it scanned and indeed its the maf sensor. I haven't cleaned it, however I may opt to buy a new one outright. I'm not sure if the previous owner replaced it before, because mine has part# AFH50M-05 and its a A1 Cardone to my knowledge which is horrible from what I hear, so if I get a new one I may go for a AC Delco, cheers!