I had the same type of symptoms on my 300CE. I adjusted the EHA and it's now MUCH improved.

To do this, you remove the EHA from the side of the fuel distributor.

Then there is a small adjuster screw on the back of it. Turning clockwise richens the mixture and counter-clockwise leans it out.

I had to turn my one a quarter of a turn CW to richen it up and the car runs really well now; no more hesitation when cold...

__________________
1988 300CE 124.050 M103.983
1986 190E 201.024 M102.962