High HC is a result of misfire (unburnt fuel). I would start with secondary ignition, cap, rotor, wires, plugs, coil, & OR vacuum leak in the intake area. How old is the O2 sensor?? What was the last time engine tune(secondary ign.) was checked? If new plugs are needed don't forget to check compression!

__________________
MERCEDES Benz Master Guild Technician (6 TIMES)
ASE Master Technician
Mercedes Benz Star Technician (2 times)
44 years foreign automotive repair
27 Years M.B. Shop foreman (dealer)
MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)
Retired Moderator