low idle on 2002 Chevrolet Astro

when i start the car its run fine and when the car warm up theres a low idle what the matter with the car why is there a low idle? and the Service Engine soon light is on.

Asked by for the 2002 Chevrolet Astro
Since a fault code has been set , if you scan the vehicle the information you get will probably answer your question.
Many auto parts stores will scan vehicles as a courtesy.
1 more answer
random missfire, also your mpg drops as you are driving, ?? i havethe same problem !!there is a idle air control vave but that didnt fix my problem ?