Hi bro @DanzE90,
Just to share with you and all the E9x owners here regarding the outcome.
Tried started it yesterday morning. Again RPM dropped till 500 and engine about to stall, so have to slightly step on the throttle to maintain the RPM @ 800-900.
Drove it to Auto Bavaria immediately since no fault codes were thrown to me nor loss of power suffered from the car.
Upon arriving at AB, the car seems fine. Left it for one full day there for them to run through diagnostics on the car. I was there the whole day as well to monitor.
Everything turned out to be fine and my car seems to be healthy. They test drove the car and everything was normal. Spark plugs, ignition coil, a few mentioned sensors and starter seems to be normal and healthy.
But the senior mechanic there did mentioned, MIGHT or MIGHT NOT BE fuel pump showing signs.
Was a smooth drive home from AB after that. And have since left parked at the carpark bay. Will usually use it on weekends only.
My car is exactly 6 years old this 24th February 2016. Done only genuine 26k mileage. Been with AB service centre since day 1 it left the showroom. And this is the first time I've encountered this issue. Still puzzled though. Haven't been sleeping well since. Heh!