Air Intake Idler Valve?

[Rubberhead]

My V8, 2003 XLT is making a chattering noise when I back off of the throttle or when engine load decreases like when the AC shuts off.

A guy at my Ford dealer told me it was something like a "air intake idler valve". I asked what would happen if it breaks and he said they usually fail closed so the engine will idle down to the point of cutting off if don't keep my foot on the gas.

I can definately feel it vibrate when I put my hand on the box with the air filter.

Does any of this sound familiar? Does anyone know the real name for such a part? I feel certain I can replace it myself if I just knew what part to get.

Any help is apperciated - Thanks.

 

[E.B. Cornburner]

The Idle Air Control (IAC) motor or valve as it's correctly named, is attatched to the throttle body (where the intake tube attatches to the engine). The component out near the airbox is the Mass Airflow (MAF) sensor. I've never heard of one of these vibrating! The IAC motor can screw up and I suppose vibrate, but again, I've never experienced this.
How is your idle quality? Does it idle up when cold, then come down as it warms up?

To people in the know: Does the '03 use Drive-By-Wire throttle, or still use a cable?

If it's DBW, it could be the throttle servo acting up. I've heard of failures with these.

 

[Rubberhead]

It idles perfectly. Starts at around 1,300 then idles down to somewhere near 1,000 maybe a little less.

The "virbration" is more audible than anything I can feel from the driver's seat. However, when I was holding the air intake housing, I could feel it chatter briefly when it made sound.

The only way I know to get it to make the sound when it is in park is to turn off the AC. It does it a lot worse when I've let off of the gas to come to a stop. I'll see if I can get to the Idle Air Control motor.

Thanks so much for your help. I'll let you know if how this turns out.

Thanks again.