I cleaned my IAB and have read since that cleaning the IAB isn't a good idea. The guy said that the IAB will never be the same through cleaning and the only real fix was to buy a new one.
Idle speed isn't going to make any difference on a surging problem (but 650 is kinda low). My car did this for a couple days after the new combo. How long have you had the car running since hooking the battery back up? Your computer will take a couple days to get used to the new combo. Don't touch the IAB just yet.
Go take the car for a long drive and try to keep a constant RPM for at least 10 minutes. And give it a couple days before changing anything.
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