Well, I had this pulsating hissing noise and someone said this.

I bet it's your IAC (idle control motor), Ford with bad IAC makes a hissing noise on idle. Try to unplug it, the engine is going to die when you do that, but listen if the noise goes away right when you unplug it just before the engine dies. If it dos you have a bad IAC.

So where is it exactly? Hopefully its that and no exhaust or spark plug leak.

 

Without going out into the rain for a looksee to double check, I'm almost positive it's the silver-looking canister (approximately 1.75" in diameter if memory serves correctly) on the right side (passenger) of the engine attached to the upper intake. In fact, I'm about 95% sure.

Jim

 

well, to answer your question, the Idle Control Motor is just what it says!!! The computer reads engine RPM and adjusts the ICM accordingly.

I had a '87 Escort that had a bad one, but it had 200,000 miles on it when it went.

I also didn't realize that these trucks had one. I thought they just had one one throttle body injected vehicles.

 

I think that stands for Idle Air Control. If I remember correctly it feeds the engine air when the butterflys are closed at idle.

Jim you nailed the location dead on.