I've been having a problem with my 94 z28's idle. After I drive the car for around 30 minutes and come to a stop, sometimes the engine revs/surges up past 1000rpm. It's enough that I need to hold the brake very hard to keep from lurching forward. I made a Freescan log today of the car idling after a fairly long drive. I left the car in gear for most of the time and you can see around the 29900 mark that it revs to 800rpm (550 desired). I then shifted it to park and it revved up to 825rpm (650 desired) around the 30580 mark. I've done a lot of reading and I'm thinking it might be the IAC, but then again I'm a noobie when it comes to all these readings. Any help would be greatly appreciated. Thanks.

Here's my log

Also just wondering, shouldn't my battery voltage be higher than 12.3?