Take it from a mechanic. Pull the IAC, clean it with a can of carb cleaner, while you're at it clean the whole throttle body. This will take the whole can of cleaner and a couple of towels if you do it right. The IAC runs off of vacuum and any "gum" will affect its performance. Afterwards it will take it a minute to run right again as it will have it's "snoot" full of cleaner. Reset the light (you can do it manually by unhooking the battery cable for about 10-15 minutes). If problem reoccures change IAC. Oh yeah. IAC stands for idle air control. It's found on the side of the intake plenum. Don't confuse it with the TPS (throttle position sensor). If you need more info or pictures let me know.