Hi. I am a new member. I have a 1990 500sl that starts first time every time. However, there is a slight misfire at about 1500 revs and the power seems to be down. Also, for no reason, the power cuts almost completely and I have to press the accelerator to the floor to get the car to move at all. This is cured, as often as not, by switching off and starting again. Have replaced plugs. leads, dis caps and rotor arms, one coil and fuel filter, with no change. Any ideas?