Bring the car to me I'll fix it for you. My 190 had the same problem and it took me months to figure it out, no mechanic would offer to look things over to the detail that i have looked them over myself, every one just wanted me to replace things, even I sometimes wanted to do the same, but in the end, I could have fixed the problem with nothing more then a multimeter and a 3mm allen key, but I replaced all the usual parts, distributor cap, rotor arm, spark plugs and wires. Now my 18 year old 190 has the smoothes idle and acceleration you can imagine.
Tip #1 - check the EHA current, and go from there.
you can read some of my previous mosts on hesitation about how to do this, just look for "Hesitation - History" yes I had a lot of time to come up with that one