I have a 1997 Grand Prix, 3.8L non-supercharged with 113K Miles. The car shudders, sort of like hestitates when I attempt to accelerate at
40 to 60 miles/hr speeds. We thought the shuddering was Transmission related... it turns out that about two weeks after the shuddering started, the car started slamming in gear and we replaced the transmission early this week, with a new Goodwrench one. Now with the new trans the slamming is gone but the Shuddering remains.
The SERVICE ENGINE SOON light just recently come on, my mechanic hooked up his hand held diagnostic computer and determined the problem as RANDON MISFIRING (based on the diagnostic code generated). He says we need to start by replacing wiring, plugs, coils and tune up (in this order) to eliminate the problem. A local dealer did the 100K tune-up at 95K mles and about a year back. Does anyone know what the problem may be?? Please help! Thanks in advance.