BMW 3 Series 1st gear eccellerating jerk hot or cold

When I pull away with the clutch out its like it shuts off and comes back on and if your not ready for it its a disaster. Over time I have learned to pull away steady then if I feel through Fly by wire its coming I let off throttle otherwise it can get jerky. I don't know if this other problem is connected but if I rev up the car in neutral parked up and repeatedly rev the same revs like thrum thrum for say ten times it will carry on by itself copying what revs I have just done. The only way to stop this is to switch off ignition and restart then its back to normal. The car drives good on motorway I can get around 37mpg on a long run, it does idle very well its just the pull away jerk it does not do it every time its one day I may not get the problem on London roads stopping and pulling away but like I said I have got use to it but that does not stop the problem. When it wants to jerk it will only good thing is Im always ready for it and ease off throttle not a very enjoyable thing to have and I have had this problem since I purchased the car in 2012. I hope this is helpful to someone to maybe diagnose the problem. Look forward to hearing from somebody in near future. Thanks Johny.