Welcome Visitor! Please take a few seconds and bmoore58
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Hey, folks. I've seen this here before, but want to share mine, too. I have a 99 4.0 with 179,000 miles. I know. Barely broken in! Anyway, I got the ol' P1506 code for Idle Air Control. When I start the engine, it idles around 13-1400 rpm. When I drive it at lower sppeeds, it's like having the cruise control engaged. I take it out on the road and it's fine, until I have to stop. When I stop, it idles about 2,000, then eases down to about 1,300. Way too high! I have replaced the IAC valve twice, the second one is a Motorcraft. I removed and cleaned the throttle body, and checked the TPS. Everything seems good. I have ordered a new Motorcraft TPS. I have sprayed carb cleaner at every joint, fitting, hose, and anything else with no change in idle, so I'm guessing no vacuum leaks. PCV valve is cleans and rattles like a Diamondback. Have checked hoses, and can't find a crack or a bad spot anywhere. I'm running out of things to check and places to look. Anyone have any ideas?
