" Just curious, how important is it to line up the larger holes on the IAC gasket when re-installing? It has a little bit of play and when both bolts where back on i couldnt tell how centered it was. I took the car out for a test drive and it seemed just ok."
If it is not leaking, you should be fine. If it is leaking, you will know (crappy idle again).
"I noticed a slight lag in powerband. Will it take the computer a little while to adjust?"
Yes, give it a day or two.
