idle speed rises

[T-5 2.3]

hello everyone I am new. I have a 1998 S70 T-5 2.3 liter. recently I noticed after I drive and shift the car in park the idle rises. I took my obdII SCANNER and readings indicate (PASS) my only guess was either the idle speed valve or throttle position sensor. I so far only replace the ISV, drove the car the highway. came home shift the car in park BOOM the idle rose then drop back to normal. I love the car but it sucks when I can't drive it. any suggestion for the cure. I'VE clean the throttle body also.thanks T-5 2.3