throttle air bypass valve
 

I was looking in my haynes manual and i came across a diagram showing me exactly where the air bypass valve is located, now i have owned another mustang but it was a 2.3 and has a similar, if not the same air bypass valve, my question here is would a throttle air bypass valve from a 2.3 fit a 5.0, i am guessing right now the answer is no because of the different air ratio's from a 2.3 to a 5.0, well anyways let me now if anyone has attemted this.

Yes, its the same valve as far as I know. The calibration for the amount of bypass is held in the computer and is based on throttle position, engine rpm and engine load.