Originally posted by Shore 96 Teg
This happened in my Lude. It was the Air Idle Control Valve aka Idle Air Control valve. or as dubster said the IAC Valve 
The other two he mentioned are a possibility. Hope its a vaccuum leak. IAC's can be a little on the pricey side especially after you add labor. I had to cause i had no idea how to take mine off.
Two screws and two coolant lines! :thumbup: