2004 Chevy Optra when stopped at a light the car idols funn

Has the check engine light come on? There are several things that can cause this. Without an trouble code, it becomes a guessing game. THat is why I asked about the light.

Also, have you checked to see if there are any loose, damaged, or disonnected vacuum lines?

Finally, my gut feeling is the problem is coming from the ambient temp sensor. However, as I mentioned, that is a guess without the light coming on. Does the problem happen regardless of engine temp?

there is no engine light that goes on and it seems to do this even if the car is cold or warm.