Having recently "inherited" my c250td 1998 model and having only drove approx 100 miles since I got it, the car lost its power, if I hadnt known better I would have said it was out of diesel, It was towed into the garage who said they could find no fault i.e. "it is working" ! It did for about 10 miles and again lost power, fuel filter has been changed twice and it goes for about 10 or 15 miles then loses power again. Any suggestions?