I would check the OVP Relay and the Fuel pump relay.
You may also want to check out the plug to coil connectors.

Also, you can request the MB dealership to check the code using HTT and then you will know if the mixture is too rich or lean. You can also have them check the partial adaptation values.

A Scope can tell you what's going on at each cylinder, (vaccum leaks, bad injectors, spark plugs).

Fuel pressure check is also a good idea.

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Zafar
94 E320 58000 Miles