idle problems

hi i have a 95 eagle talon tsi and i have a problem once in awhile the car likes to idle at 1500rpms for no reason i have replaced the idle air control valve and it still does it i have checked the vacuum lines and there all fine it wont high idle at first start up but when u go to drive it it does it after u put the car in park but if u park and chill for awhile and start it again it wont do it tell u drive so plz tell me what is going on.