What's causing a lack of power under acceleration on my BMW 530d automatic?

I have a 2003 BMW 530d Auto (E60) that has done 124,000 miles. I recently experienced a sort of power lag, by this I mean when doing speeds of 75 - 85 mph and you press the accelerator (not kick-down but a progressive push) to overtake, the car increases speed but does not have that "torque feeling" that you'd expect. I also noticed that there was a consistant pushing, as if the car wanted to go but didn't. This happened three or four times, and then the car went as it should. A specialist changed the Mass Air Flow sensor and, for 10 minutes, the power was resumed. After 15 mins of motorway driving, every time I floored the accelerator, I was getting plumes of black soot-like fumes coming from the exhaust which were visible in my rear view mirror. Could you please advise as to what the problem could be?

Asked on 13 June 2010 by Javers

Answered by Honest John
Failed turbo bearing and turbo oil seals. You need a new turbo.
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