What rpm do you have at warm idle? I may get corrected here, but "normal" warm idle should be 750ish.

If you have normal warm idle, I believe it would point in the direction of warm up regulator problem (if so equipped) and/or whatever else controls cold idle speed.

If this describes your situation, search "warm up regulator" before you dive into the "high idle" search (high idle is so common, you'll get a gajillion threads to sort through and could grow old getting through all of them).

My invoice ($.02) to follow...

Good luck
Kevin

__________________
"Dangerous with a wrench...and not smart enough to know it"

Stable (in order of acqusition):
'84 500SL, 280SEL (Euros)
'77 280SE. '90 560SEL
'79 450SEL 6.9,
'95 C280 (totalled by daughter 8/07)
'81 280SL (rescued) '88 300CE
'86 560SEC '95 C36
'01 CL55

DD's: '04 S500 4Matic (SWMBO)
'04 F150 Crew