I posted this in the cobalt forum, but thought that I might get a better response here since this is a general type of question.

I have a 2007 chevy cobalt. It idles a little rough when stopped and in drive, it's even worse when the A/C is running. I did have a small accident (hit a deer, actually the deer hit me). They had to replace the housing for the air intake, bumber and hood. However, I can't remember if it did this before or not! I might just be paying more attention now(and using the A/C more because it's hot).

In any case, I just wanted to check and see if this a common problem or not; this is a small engine (ecotech) so I can almost understand the A/C putting a little load on the engine and causinga slightvibration. However, even with the A/C off I still get a slight but noticable rough idle/vibration.

I don't 'think' the accident could have broke the motor mounts or anything like that. But is there a chance something like that could be the problem?

No engine lights or other problems.

Thank you!