Engine Stalling
 

I have a 2007 manual Mini Cooper. I always put V Power petrol in the car but just over a week ago I noticed that when I came to stopping the engine seemed to struggle like it was about to stall. The problem is now if I am coming to a stop sign or a traffic light on red and I don't keep the revs up the car will stall. We have checked the battery and alternator but they seem to be ok. Can anybody help??