Wandering Idle

I have a BMW 320I and am having an idle problem. If I let off the gas while driving, the idle will drop to an almost stall and then jump back to around 750. At idle it will wander to almost stall (0 rpm) to 750 back and forth. I can make the problem go away by disconnecting the posituve cranlcase ventilation tube (the tiny tube on the bottom of the PCV valve. What would cause this. I replace the small line and still have the problem when I disconnect the PCV. ANy help would be greatly appreciated.

Mike

Check you Idle Contol Value . . . have you cleaned it?

What year is your car?

Cleaned Idle Control Valve. The car runs fine when the crankcase vent hose is disconnected. It immediately coughes and then stalls when the vent is plugged back in.