When was the last time the tranny fluid (including t-convertor) and filter were changed?
Did you use an OEM filter, was the filter gasket present and in good condition? Did the filter seat without resistance? Was it the proper filter?
Are you certain that the proper fluid was used?
Did you go with synthetic fluid? If so name of brand?
Was it changed using gravity or a power flusher?
Not sure about your tranny, but with mine (both Benz's) the vacuum modulator setting is a big deal.
Inquiring minds got to know?