I have a 2003 MB C230 Kompressor Sport Coupe (hatchback). I bought it used 4 weeks ago and everything passed inspections. Lately the engine seems to be really loud and the RPMS are going to 3.5-4.0 when I am going fairly slow. It seems to really jerk when it switches gears and the RPM goes really high without the car gaining much speed (I have an automatic transmission). I thought maybe I had it in winter mode but it is in "S" mode. IS there anything simple that could be causing this. Sometimes the RPM gets to 5 and really loud and I am scared I am going to blow the motor (when this happens I am not pressing the gas hard at all). please help!!!