I have a '04 GMC with a few upgrades one of which is a Vara-Ram CAI, its been on for over a year so I don't think its the problem. Anyhow, for a few weeks now my truck will idle so low that it will sometimes stall. Seems to happen more when its up to temp. I had a friend scan the truck, nothing. I cleaned the filter and the MAF with contact cleaner, removerd battery cables to get it to relearn, nothing still does it. Gas milage is a bit poorer than usual also. Is there a throttle position sensor or something that could be out of whack? Would it trip a code?

thanks