2011 E90 Automatic random stall at startup

[Deltanz 2]

Hey folks so just gotten my 2011 E90 320I and everything was going fine  for the first few days but now I seem to have a problem where sometimes at startup the car will turn over but then the revs drop and it dies. Sometimes it will pick itself up but not always 

 

Have also noticed that this has happened after I've fueled the car up  and seemed to settle back to normal after a day or so which has me a bit confused.

 

No codes are been thrown and no CEL either 

 

The video i've loaded shows what it does but sadly this time it decided to actually save itself.

I've also noticed sometimes it is sounding almost like a diesel which i've loaded as well

 

Any ideas would be great as I'll be talking to the dealer again about this and would like some advice from fellow owners