Hi, I'm new to BMW & still finding my feet a little. I have a 2003 (E46) 316i. The car has a very rough idle and when I drive it the mph does not read as it should for what the revs read. If I put my foot down, it runs rough, like it's misfiring for a second or 2 then it kicks in & sounds as it should, all cylinders firing, although the power is just not there and like I said before the rph do not match what the mph should read i.e. 4,000 revs accelerating but speedo creeping up from 30 to 40mph.......Unplug the Mass air sensor and she runs near on perfect!!! I know it's not the mass air sensor though as I have already replaced this...result remains the same...Help!! Oh, one other thing...the power train light is on when the mass air sensor is disconnected, it goes out when connected.