1992 Ford Explorer Idle

Although I cannot answer your question for certain without my crystal ball. ;). I would suspect your idle air control motor is to blame. I would first try removing it and cleaning it out with some carburetor or throttle body cleaner. It should be toward the top of the throttle body (where the air duct enters the top of the engine) and usually has a silver, cylinder shaped end opposite a 2-wire plug and has 2 bolts holding it on. And although a 1992 has the OBD1 computer on it, troublecodes may also be present. If the check engine light is on, I would have the codes read at your local parts store before proceeding further.