I was driving to work this morning with the A/C on and noticed that the truck was idling weird when I was at the red light: the RPMs would drop and go back up every 4-5 seconds. I have cleaned the IAC in the past (a couple years ago) because I was having a similar issue when I would shift the truck into park, but it didn't solve anything. Would it seem that the IAC has gone bad and needs to be replaced?