IAC vs IAC EA vs steps

Hey guys,

Just started tuning a friend's TSP torquer cam and was looking for a little advice. I read the idle tuning threads and what I got out of it is, use the RAF pids and adjust the Desired Airflow table. After that, there's some conflicting info....drill the tb...don't drill the tb... He's gone and drilled the tb a little bit (enlarged the existing hole slightly), but it wasn't enough to keep the car running on its own. Because we were short on time, I just added 2 g/s to the Des. Air. table and it runs now. But, I still need to do the RAF pid logging/tweaking. What I'm stuck on is the relationship of the IAC to the steps and what it's actually doing to the tb.

1) Does the IAC actually move the blade or does it control idle through one of the holes on the inside of the tb?
2) What kinds of adjustments should I make to the IAC Eff. Area table to compensate for the drilling (and soon to come set screw adjustment) in order to get the steps back down?

An IAC (as implemented by GM) is actually a solenoid-controlled air bypass valve. The further it opens, the more air is allowed to flow through it, thereby bypassing the throttle plate. The reason that idle speed doesn't usually change when a throttle stop screw is adjusted is that the IAC increases or decreases air flow in response to increases or decreases in air flow pass the throttle plate. It doesn't actually measure air flow, the PCM just tries to maintain the programmed idle speed and moves the IAC position as required. However, if the IAC is full closed or fully open, adjusting the throttle stop screw will change idle speed because the IAC can't move any further. As an example, if the throttle stop screw has the plate opened so far that the IAC is completely closed, tuning it in further will increase idle speed because the IAC can't reduce air flow any further. On the other hand, if the throttle plate is restricting air flow to the point that the IAC is wide open, putting an additional load on the engine (such as turning on the AC) may cause it to stall because the IAC can't increase air flow any further.
Increasing the size of the hole in the throttle plate essentially increases IAC effective area across the board by a fixed amount-- it increases total air flow but obviously doesn't change as air flow past the IAC changes.

So if I increase the airflow around the throttle plate using the set screw to reduce IAC steps by ~100, what do I do besides a TPS reset?

(I'm assuming a TPS reset just means unplug the TPS, turn the ignition to run for about 5 minutes, turn off the ignition, and plug the TPS back in.?.)