So it turned out that someone before me had messed with the stop on the throttle plate, so that it didn't go closed far enough - that is what was holding the idle up too high. Apparently, if the pcm sees the idle too high, it occasionally will tweak the iac to try to get it to move closed, which it cannot do if its already closed.
After adjusting the throttle plate to a position close to where it should be from the factory, the iac actually controls the idle just fine. Now, I just need to get a good vss on the car (I have one, just needs put on), and everything should be fine.
Thanks for all your inputs!