It is important that you tell us the year and mileage of your car. There are two very different C280 automobiles. There is the M104 engined 1994-1996 cars with inline six and four speed automatic. There is the 1997 models with M104 engine (inline engine) and five speed transmission. There are the 1998-2000 cars with M112 V-6 engine and five speed tranny.
Some of the cars are OBD-I and others OBD-II. I think some have conventional throttle actuation, and others have drive-by-wire.
Some thoughts include a possible misfire or fuel problem. Does the car suffer any other kind of symptom other than a shake through the pedal?
1998 C230 "Black Betty"