bad engine idle

i have a f250 super duty ford pickup,i have a air leak some where on the motor that is making the engine idle fast and idle rough i tapped around on the irc ,i think that is what its called ,and it now idles at 12oo rpms but still to fast on ilde and can hear air leak on the motor but can not find it ,any ideas>:screwy:

Get a can of WD-40 and spay everywhere you hear the noise. When the WD-40 hits the leak the noise will change or stop.

What motor? 5.4? Ill second that air leak idea, you can also use brake parts cleaner.