get the engine nice and hot
disconnect the IAC, and spout
close the throttle stop, to lowest rpm to where it just stalls, open the the stop maybe 1/8th turn, ensure the throttle blade does not stick in its bore
turn engine off if did not stall
test by opening to WOT and let it snap closed, then open slowly with your fingers, there should be NO binding
repeat the 1/8th if necessary,,,,,,,
unhook neg cable from battery, step on brake pedal a few times, reconnect cable restart, and give a few quick stabs of throttle, and let return to idle......
that might get you in the ball park.
89 GT gr-40, KB2200(10psi), tweecer R/T,LC-1, 22gal cell, w/tailpipes.