Once it gets warm the car will idle in park from 1000rpm's up to 1500 rpms and back down then back up. it will just sit there and surge up and down constantly. The engine is still running smooth, but just hunting for the right idle. It isn't misfiring, and you don't really notice it near as bad if it is in gear. Just an anoying surge. No check engine light on either. give me ideas if you can. Thanks, Nate