Our 2001 Grand Prix GTP hit 100k miles last month and was going strong but then some problems arose recently.
1. When accelerating hard sometimes the CEL light flashes then goes away.
2. When driving 35-50mph the car shakes bad and the sensation feels like it's coming more from the bottom. It also shakes but not as bad when going 65-80 mph.
3. This one problem I've had problems reproducing but it has happened once or twice. But sometimes when the car shifts when I'm merging on the highway. The RPM's will fluctuate between 1500 RPM and 2000PM for a few times then the car finally will switch gear.
I changed the spark plugs and the spark plug wires two months ago as part of routine maintenance. I cleaned out the throttle body and put some fuel injector cleaner in the tank. The car feels like it got some low end power back but those three problems still show up. Any help would be appreciated.
I don't know how the previous owners handled this car but, seriously I didn't imagine so many problems arising.
