I have a 94 C220, It has 210 Thousand miles I have kept it alive for the past 5 years and drive 70 miles a day in it....
The only problem with it is now it is blowing unused gas out the back of the car and it is black.
I have replaced the main engine wiring harness so I could get a reading from a computer but I still can not get a reading.
I am about to replace the three other harnesses so hopefully I can get a reading.
I am thinking about replacing the Oxygen sensor and the mass air flow sensor.
Am I heading into the right direction or am I just keeping the parts guy employed?

Please help I need this old faithful alive