f 150 rough idle

Sep 29, 2007 1 Replies

My '97 f 150 has an intermittant rough idle. Some times it is smooth. Only at idle. Smoothes out as soon as i accelerate. It has a 4.2 v6, automatic with 101,000 miles. plugs replaced at 85,000.


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Check the Idle Air Compensator (IAC) motor. It's normally on the throttle body somewhere (NOT THE THROTTLE POSITION SENSOR!!!). I had a

99 Ranger that did the same thing and I pulled the IAC off and loaded it down with carb and choke cleaner then put it back on. Voila!

It's not a cheap part to replace which is why I say try this.

Also, plugs were replaced but what about the wires? A bad wire can crap one out too.

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