I have a 2003 Buick Regal with 188000 miles and a couple of months ago, I was getting a high idle happening on the car when turning it on (about 2000RPM). And when putting into gear, it obviously is rough. Have tried to hit the gas to possibly take it out of the idle, but nothing has worked. It also will not drop out of the high RPM's in neutral.
I have taken the car to two different mechanics and they can't determine the cause other than to say they could replace one or two different sensors but that they may not be the issue.
Over a month ago, the car ramp to 5000 RPM's and it took everything I could to hold the brake to stop, but it still shot through the intersection. Got it to a shop and they said it was a work throttle cable that was catching.
This seemed to work until yesterday when it started again. I will add that there seems to be this issue if the car is left idling for a period of time. I also have been noticing a strong exhaust smell lately.