Don't think this is the ABS, it cuts out below 3 or 5 mph, what you are experiencing is at lower than walking pace speed, right? Worse in Drive than coasting to a stop in Neutral?. Acid test is to disable the ABS (unplug the computer) and see if it still happens.
Both my Mercs have done this, it also seems to be worse in damp weather and I have put it down to a combination of cheap aftermarket pads and possible worn suspension bushes.
Any comment from the pros?
'08 Chrysler 300CRD (MB OM 642 engine)
'95 E220 estate
'89 230TE (R.I.P.)