I got the feeling this is one of those faults that everyone who knows these
engines knows about. I have a 3litre M60 engine in my 1993 530i with 106k
miles on the clock.
It seems to have a problem somes when the engine revs down that it'll bounce
off the idle point (around 550rpm) and briefly bounce back upto 1200rpm or
so, once, before settling down to idle. Its as if the engine controller
thinks that the engine is going to stall and tries to recover the situation
by blipping the throttle open. Often I can make it do this by manouvering
the steering wheel at idle, and somehow the load from the pump just causes
it to surge briefly. Other than this i have no problems with engine running
at all, other than maybe a slight misfire at idle usually on hot days!
Someone suggested that it might be the idle control stepper motor?
Any ideas definately welcome!