IAC Valve Reset Procedure (4.3L)
WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2003 GMC Savana Special, 2003 GMC Savana Camper Special, 2003 GMC Savana, 2003 Chevrolet RV Cutaway, and 2003 Chevrolet Cutaway. However, it is still accessible from the selected car via links, so may be relevant.
Turn ignition on for 20 seconds. Turn ignition off for 10 seconds. Start the engine. Check for the proper idle speed.