I had a very similar problem because of an O2 sensor going bad. As soon as lambda control kciked in closed loop, the car would start hesitating like no tomorrow, but after a little bit of driving like this, it all went away, then the sensor died completely and I never got into close loop.

Do some tests, do a full tune up. Post your results.

xp

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1985 190E 2.3L - a constant project.