On occasional cold starts you get 10 seconds of rough idle...and you've spend 400€ and want to chase this more????

Im not sure a BMW dealer will diagnose this any better than an indy- they tend to be the 'whats the code, we'll do what the computer tells us' variety.

Gas cars had idle air control valves that operate during cold start- when they get fouled, you can get that kind of behavior.. I am not that familiar with BMW diesels, lets see if someone chimes in.

Oh, smokey has a good question.....