Engine Management Light - HELP!!

Hi there, my X3 went in for a service on Friday. The engine management light had previously came on earlier in the week but went straight back off again. I mentioned to the garage when I dropped it off that this had happened and they said they would plug it in to see what codes came up. It came up with Air Flow Sensor Fault. After the service he explained he had re-newed the air flow/filter thingy (not too good with names but it's the long white thing that sits next to the engine which he said was rather hard to get to lol) which looked like it had never been changed! Anyhow on driving the car home the light came on and has been since, there's also a feeling of 'dirty diesel' (i.e. the car is juddering when driving). In the morning it struggles to start - it's starts then cuts out but after 3rd attempt it goes. ANY IDEAS?????

Think I've put this thread in the wrong place!

Correct. This is the current generation X3 board (2011+) The previous generation board is located here:

http://www.bimmerfest.com/forums/forumdisplay.php?f=65