Here is the Idle Control Valve:
Here is a thread on M3 Forum about cleaning and symptoms and checking it to see if it's frozen in place.
http://www.m3forum.net/m3forum/showt...+control+valve
Everybody might need some more info to completely help you out. When does it do this? At first start or coming to a stop. Hot engine or cold engine?
The hose clamps that hold that on are crimp clamps and are narrower than your average hose clamp. Keep that in mind.