Inside the IAC there's a bi-metalic strip that compensates for temperature differences in idle air. The rest position is around 0.04" or 1 mm opening at room temp. If the opening is different than that, it should be replaced, but can also be adjusted by the set screw that is potted and sealed.(not reccomended as it can throw off the IAC controller settings for the valvee to operate correctly)

Most issues with a bad idle stem from the small orifices that are in the throttle body and get clogged.
Also don't use full strenght carb cleaner to clean the IAC, nor move the valve with a metal object. Use a 50/50 mix of carb cleaner & WD-40, Q-tips and a pencil eraser to hold open the valve while cleaning. Flooding the valve with carb cleaner can damage the motor windings.