High idle at start up. please help

[HeadUp240]

First of all please dont say 'SEARCH IT' because ive tried and the only thing i can find is topics with peoples idle going up and down but mine doesnt do that. When i start my car my idle goes to 2000 and stays there for 5 to 10 minutes and goes back to normal. but if i turn it off for like 20 minutes and start it back up it goes straight back up to 2000. any ideas?