Hi, read your post of similar problem I had with my '89 190E 2.6 w/ 170K miles; long story short, it ended up to be the crank position sensor that fixed the problem even though my old sensor measured at 900 ohms (within specs).
I have shotgunned my misfortune by replacing parts one by one; OVP relay, fuel pump relay, EZL module, ignition coil, and finally the crank position sensor.
I swapped the old parts in after crank position sensor replacement to be sure it was a good fix, it's still running as of today (6 weeks after).
I reinstalled all the new parts since I can't return electrical item, but I have a hunch you may have the same problem as I. Just my thought.