Bought my BMW 2 days ago and the dealer can't get a mechanic to look at it this week. When I got the keys I started it up and the car stalled, didn't think much of it, restarted it and the revs were around 600, I just pressumed it had been laying around for a while. Got home, and took my mum to get her car that I had been using, got in the car started it up, stalled again, restarted low idling around 600 again. Since then the idling has been sitting at different levels, cold starts it will sit at 900 rpm. Last night I took it on a motorway run and stopped after that to find the it idling on 500 rpm. I'm an apprentice bus mechanic and an ex-car mechanic at my work said to check the air mass sensor, but I checked that earlier but I can't get it off since BMW have put awkward torque screws that have a pin in the middle so I can use my torque screwdriver to take it off. While randomly playing around with buttons in the car, I pressed a button with a logo that looks exactly like the recycling log (can anyone tell me what this does as I didn't get the onwers manual :/) by pressing that the rpm seemed to raise and stabalize, I pressed another button right underneath it, same logo but thinner, and it didn't make that much difference. After pressing that first button, it stabalized for a few seconds and the engine went back to its jittery self, but stayed at about 700 rpm. Also that button I pressed had a green light, which I pressed it and the other one on and off a couple of times and now the green light doesn't work -.- lastly I'd like to note that for some reason the car was close to stalling but the rev meter didn't seem to realise and stayed at 700rpm and the engine stabalized again. I've been screwed over with cars since I started driving can someone please give me a reasonable answer. The car was serviced before I got it, and it was a big one aswell, ALOT was done to that car.