Our 190e 2.6 (similar engine) had a few more miles (230,000) when a worn airflow meter potentiometer started causing similar symptoms, along with high idle and surging when coasting. I obtained a new (used) fuel distributor and airflow meter. Then the only problem was the hard starting and dying at stop signs.

Eventually, I realized that the new fuel distributor had too great a differential between the fuel pressures in the upper and lower chambers. That was cured by adjusting the new EHA with the secret screw on the back by 1/8 of a turn clockwise. Apparently, that is a tweak disclosed in the 300e owner's bible. It brings the pressure differential back into the range where the computer can control it with the EHA. Anyway, it cured the problem for our car.

Is it possible that your problem is related?

Andrew
1989 190e