[michael peters]

Originally Posted by Steven.walsh

Definitely the MAF sensor, (Mass Airflow Sensor).
Quick fix to 100% prove is to simply disconnect and your car will be transformed.
Some on here leave them disconnected, no detriment to the car that I know of, excepting prob wont get optimum power and fuel economy.
Then in slow time you can work out whether to replace with another Bosch MAF, mixed reports on here how long they last, I went for the RonBox Synergy II with piefberg MAF, gives extra power and better fuel economy for about same money.
Sure people will soon comment on other options as have seen quite a few of late.
To disconnect MAF remove big engine cover first one with BMW embossed on it.
Then remove remaining cover, the one the oil filler cap is part of, and where air filter sits beneath.
The MAF sensor and plug just to left of filler cap, you will need to mess with clips either side of black plug and the connector should pull free, stash connector safely somewhere in that area and have a drive, let us know how you get on.
Take care
Steve

Tried it this morning with the MAF disconnected and it was fine. Many thanks for your comprehensive reply.