The idle is controled electronically, do not try to make adjustments. My guess is that you have a vacuum leak somewhere. Check the gasket under the throttle body, it may be damaged.
1998 and up is 5650 Rpm
190@ 4400 RPM
5500 rpm
5500 RPM or 5 RPM below the banging knocking sound you just had .
110 hp @ 4800 rpm.
3000 rpm or lower
with a hot engine: should be no lower than 20 idle (usually 30 ish) and at about 3k rpm should be about 60. this is assuming using 5w-30 oil
A plugged catalytic converter could do that.
Plugged/damaged catalytic converter.
try changing fuel filtre
the 1994 mustangs have 145 @ 4000 RPM.
Anywhere from 35-65 psi. Higher psi at higher RPM's. Lower at lower RPM's.