As JEFFSR said, drain the converter too. It holds more fluid than the pan, at least in some MB cars.

I've experienced similar problems over the yrs. with non-MB cars. It took SEVERAL drain/refills of the transmission to cure. Each time you do this, drain the pan, converter and change the filter. The system
is likely full of crud & it's going to take
time to get it all out.

Mike Murrell
'91 300-SEL