You can unplug the IAC and not trigger a check engine light, but I'm betting it'd throw a code at you, if you tried to pull them. Raising the base idle mechanically with the TB set screw might get you by, but I still bet on cold starts, your car would run like hell.
When its functioning correctly, it does a nice job based upon one main thing
The combo matches the parameters in the pcm
Never forget ... those parameters are for a stock Stang
We do the hot rod parts things which changes up the air flow
How much we've changed things determines how far from being
effective the iac becomes.
I'd say you can always try JT's method of basically taking out or
most of its function and see how it goes for you.
You only got the tb bleed screw and the tb blade stop screw
for mechanical adjustments so hopefully ... you can find a
sweet spot somewhere in their range of adjustment