Rough idle first 10 minutes of driving...ICV?

[glenmore]

My 1991 300CE, ~145m, has developed a rough idle. The revs bobble a little but do not "rev search" as others have complained about. But after the car is well warmed up, the idle smooths out to normal and the revs are pretty steady. When the car is cold, handling is a little jumpy in slow forward and reverse maneuvers because of the idle. Car drives fine and never stalls. A vacuum leak or a cracked ICV hose would cause rough idle all the time? What would cause the rough idle when cold but disappear after the car has warmed up? Is my ICV on the way out?

Thanks,

glenmore
1991 300CE
2000 C280
1990 LS400