I have had a few weird problems with these.
Make sure that there is no fuel pouring in from the inside of the fuel distributor. I have had fuel drop in on the shaft of the plunger...This is unregulated fuel and will cause a miss and skip and rich condition under moderate to heavy throttle.
Also, I have replaced many coils on these.
ASE CERTIFIED MASTER AUTO TECHNICIAN
MERCEDES SPECIALIST 11 YRS