Had this bogging issue for a while but only when car up to operating temp. Checked fuel pressure and it was fine. Fitted new fuel filter anyway. Read numerous forums on the Internet on the problem with all sorts of good suggestions ranging from Cam and Crank sensors, to water temp sensors, plugs, plug leads, coils and on and on. Some things worked for some and other things worked for others.
My pet BMW mechanic was convinced it was MAF related but tried swapping that out with another - problem eased briefly then returned. We came to the conclusion that we might have an intermittent wiring fault somewhere. So we figured to start at the source - the ECU, specifically it's pin connections.
Exposed the ECU in the top righthand side of the engine bay and pulled off the big connector. Everything looked clean and tidy but just to be on the safe side after all that effort I sprayed it copiously with Isopropl Alcohol and followed that up with a good dowsing of CRC.
Nett result - the car's a flier, running even better than when I purchased it secondhand about 7 years ago!!! Whatsmore this car's done just over 275,000 kms, burning no oil, and strong as. No bogging on moderate throttle pressure as would normally be expected - not even a hint! Pulls like crazy in any gear!!
So, to all you fellow Beemer owners, if you currently have a problem similar to what I was experiencing then, before spending lots of dosh, cleanup the ECU connection.
I'm a newbie here but I hope this helps :-)
