my chevy suburban idles high in park like 1300-1500 rpm, it idles fine...

[Chieftain]

...when in drive.? 1999 chevy suburban 148,000k on speedometer, odometer stopped working around the time engine idle problem started, it only runs high when its in park or nuetral. i changed the IAC valve, the sparkplugs, and the fuel injectors. still have a check engine light on saying the idle is too high. what do i do? i dont want to take it to the dealer

 

[Lord Zarkon]

Sounds to me like you have a vacuum problem. Check your hoses for cracks, tears, and the plastic junctions for breakage. Hope it helps.