ok well recently I took my mustang to the mechanics to see if they could figure out why it was idling rough.. of course they tell me a bunch of bs that all four of my oxygen sensors are bad (not too likely) and quoted me $600... well then I had heard about the iac getting dirty and could cause rough idling.. long story short i cleaned it, my car doesn't idle near as bad, andI saved $597... plus it only took me about ten minutes to do.. soI guessthe moral of the lesson is don't take your car to a mechanic if you can do it yourself