I had similar problems on my C36 M104 engine. The biggest problem for me was that the start/stall problem was intermittent. I think humidity was a factor.

1.The crank position reference sensor (CPS) OR the wiring to the CPS can cause this problem. The wiring was cooked by engine heat and the insulation had turned to dry dust (MB bio-degradable wiring indeed!). I used the MB "repair solution" for the wiring. Later I changed the whole engine wire harness.

2. The final fix was to replaced one of the three ignition coils. Would you believe that it was the last of the three coils to be changed! The removed bad coil looked absolutely perfect and testing with a multimeter revealed nothing.

My car has run perfectly ever since.

Good luck with the 190!