If I drive somewhere close by then shut off the car and let it sit for just a few minutes(like running into a store) when I start it back up again it will idle at 2500-2700 for about 30 seconds then it drops back down to normal idle. When the car sits overnight or for a long period of time and I start it up everything is fine. It just started doing this a week or two ago. No codes on scanmaster besides a o2 code(45). IAC and TPS are set right and I have no vacuum leaks. Anyone have any ideas?