Yes the IAC can also cause it in normal driving. If it gets stuck it could be letting air in when it is not supposed to be, or it could be be closed when it should be letting in air.

When I would start my car it would idle just fine for a while like yours. Then it would start that loping crap. Also when i would start slowing down to come to a stop it would stall. Or if I was driving and put the car in neutral it would die instantly.

My buddy has his own garage and has all the nifty scanners and diagnostic tools. So we hooked it up to his comp. The scanner didn't pic up that the IAC was bad so we didn't think about it. What it did show was that when the car started doing that loping idle shit the A/F ratio went extremely lean. Our initial thought was that it was sucking in air from around the head or intake or something, not the case... What was happening was the ecm was trying to close the IAC and open up EGR flow, but the IAC was not functioning properly, so it would stay open to much and let air in. At the same time the EGR flow was also going in. Now you have way to much air flow. LEAN. I mean very lean.

If yours is going as lean as mine was, you shouldn't even be starting it.

Take my word for it or not. Maybe yours is something different but I doubt it.