Thread: On to my next problem, rough idle!!!

So I finally got my car to run and no more coolant mixing with oil because of the lim gasket replacement. Now on to my next problem. My cars idle is horrible. The rpm gauge jumps up and down and the exhaust sounds like its choking and using all its energy to run. I had this problem before an egr delete and before I replaced the lim gaskets. There are no check engine codes either. I also replaced the vacuum lines and the problem still exists. Any ideas? Thanks

99 grand prix gtp

Idle air control valve?

would that throw a code?

not until it happens on 2 or three consecutive drive cycles

this happens every time i drive and has been happening for awhile

Well, a drive cycle doesn't just mean turn the car on and drive around...it's a long drawn out thing. Like the car needs to start up below a specific temp, wait a certain amount of time at idle, drive for a certain amount of time at a given speed, stop and idle some more. It's kinda a pain in the nutsack.