it may just be an adjustment of the bowden cable - check this thread out:
and here's the thread where Steve B. and Mike F. weighed in and told me about valve body adjustments. this would be useful to you if your car also has lower than normal shiftpoints while accelerating.
What controls Full Throttle/Kickdown on M104?
reviewing my car's history i discovered that the bowden cable and the vacuum modulator were both replaced after they replaced the transmission. something definitely fishy going on in my tranny. i have an appointment to see a local MB indy about it and will post results.