I have a bmw 316i t reg. Cars been running fine and all of a sudden it just lost all power did start fine sit there running but just no power. At first I could get up to about 50mph and that was it then it just felt like it was really pulling back and would not go over 20. It won't rev over 3500rpm and won't drive over 10-20mph. Does any 1 no what this could be?