I have a 94 C280 that surges between 500rpm-1000rpm and slight misfire. It smells rich but I don't have a scan tool to read the Oxygen sensor. Is thier a way to read the O2 without a scan tool?
I have replaced the problem engine wiring harnes.

 

usually caused by a vacuum leak. spray carb cleaner around all the areas and itll help find leaks. check all the vacuum lines, plastic and rubber. air mass sensor can do that too. dirty throttle body too.

 

Could also be the Mass Air Flow sensor in the intake path.
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