I had this too and an ATF change did not cure it. In my case it seems to be the idle speed. If I wait a minute to allow it to drop from 1500 to about 1100 all is fine.
1989 2.5-16 , 1993 AMG 320 Coupe , C36 Engined 190 , 190 Evo II No 235 ( Now Sold )
I think that these transmissions have a vacuum adjuster on the LHS of the 'box , it is under a rubber cover about the size of a 50p piece . Failing that , check that the vacuum pipe is not corroded .
Had the same thing with my 300CE and it was the front coupling - it was like a new box when i changed it (i also had a full ATF change when i bought the car). I've attached a link to the thread i put up: