I have a base model O5 Impala. It had been having trouble starting since i bought it used 180k+ miles. In any case I took it to the shop and they cleaned out the fuel system, fuel filter, injectors etc. Air filter and battery have been done and the plugs and wires are all new as well. It still has some trouble starting after the shop, but that is no longer my concern as I can start it with assistance from the pedal. Now it seems to accelerate strangely on its own. It applies enough throttle to get me to about 25 from a stand still. I suspected the cruise, but that wasn’t it after I turned the car off and back on it went away. It came back again after I shifted the car from neutral to drive or from a lower gear back into drive. I can still stop with my brakes, but it revs up on its own and turning the car off only seems to solve it temporarily. Help???
Sounds like and IAC issue.
I think a vacuum leak might cause these symptoms too. Look for deteriorated vacuum hoses or ones that have come off.