Willy,
please find as a join document all the story for my 94 E220 Coupe.
First of all an injector was changed and the same behavior occurred
It start from the wiring harness which was corroded by the acid of the battery !!! After having the cable replaced my
mechanic tell me that the ECU (Engine Control Unit) is out of order.
My car is in a MD garage in south of France (Near Marseille/Toulon) and now stuck for 3 weeks.
So I wrote to MD Customer Service, in Paris, but the answer is: your car is too old and has 150 000 kilometers, so we
cannot do anything for you !
The new reference of the Bosch ECU was given by Mercedes and the Bosch references were given by the Bosch Shop .

I have order the ECU to MD yesterday and I will bring back the old one and will try to have it repaired; But by who ???

Mercedes Ref on the ECU : 015 545 9532
New Mercedes ref is : 016 545 5532

Bosch Ref on the ECU : 0261 200 442
New Bosch Ref are : 0261 203 231 and 0261 203 230

But about your problem I would like to know why the wiring harness was CHANGED ?
I wonder if you have changed the gasoline filter and checked that the injection pressure is correct. I have been told
that before starting any investigation on the ECU, they start from this checking: This is very important.

Thanks for all and waiting for answer about the cable replacement.