to clarify 4 matic is mercedes 4 wheel drive and is a completely different system from the ABS. The 2 work together so I hope I didnt confuse you. A bad abs sensor will cause this problem. To see if your sensor is bad measure the voltage at the sensor or get the abs codes stored in the computer. the code will tell you what one is faulty. Also you could pay close attention to what wheel applies when it happens.

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1986 300SDL, 211K,Dealership serviced its whole life
1991 190E 2.6(120k)
1983 300D(300k)
1977 300D(211k)