Is this an IAC leak ?

[4.6andSlicks]

I believe I have a vacuum leak somewhere so I took a stethoscope and listened around the gaskets and IAC. There's a button that sticks out the back side of the IAC that definitely is taking in air.

Is this the normal air inlet for the IAC? I thought the IAC just bypassed the throttle body with intake air from the CAI.

 

[BobHyatt]

It does. But it does produce an internal whistling as a lot of air flows through it and the opening is closed down to something pretty small. Using a stethoscope, you might well be hearing internal whistling rather than an external leak...

Try some tape to see if the leak "stops". I'll bet it probably will not.