I've got a 2004 F150 2WD pickup with 76,000 miles that now with hot weather has me using the A/C. I've gotten the check engine light symbol on the control panel and had the error code read, which was PO 506 "idle control system RPM lower than expected". With the A/C on the idle is just over 500 rpm (from gauge) and with it turned off around 750-800. From other idle posts I'm thinking of pulling things apart for general cleaning and taking a look at the Idle air control. Any others in the same situation? any suggestions welcome.