engine surging on deceleration, and idle.

[AAAGUY]

Hello,
Hoping someone can help me with a small, but very annoying problem.
I own a beautiful Black 1992 735i with 117K. When I purchased it from the original owner he mentioned a problem several years earlier. The engine would surge/buck on deceleration, and at idle (in neutral). Also the car idled a little high (about 1200-1300). When fixed, he was told it was the idle control valve. It's happening again, but after replacing the ICV, no change. I have no idea where to start looking next. Anyone here have a clue? I love this car. Was never a BMW person until I bought this one. Any help would be greatly appreciated.
Thanks, Paul.