The generic reader code P0200 can come up as a result of the following MB specific codes from stealership or a good independant MB shop:
P1220=Fuel quantity actuator (IFI) (Y23/1)
P1223=Fuel rack position sensor (Y23/1l1)
P1475=Resonance intake line switchover valve (Y22/7)
P1476=Resonance intake manifold switchover valve (Y22/6)
P1611=IFI control module (N3/7)
P1613=IFI control module (N3/7)
P1614=IFI control mudule (N3/7) or fuel metering actuator (Y23/1k1) or fuel rack position sensor (Y23/1l1)
P1617=control module not coded
P1622=Electohydraulic shut-off actuator (Y1/1)

So at least there is a range of possiblities. I haven't had this show up on my '96 E300D...yet.