I have experienced the same problem twice in my 88 300CE (M103) The first time it was the FPR. The (occasional) condition lasted a few months before it finally died. The second time it was bad ignition. Changed the rotor, wires, plugs. Gone.

Although you have a different engine and FI/ignition, my advice is to start with the cheap things & go from there.
IIRC the FPR problem arose about 6 years ago and the odo read around 115,000. The rotor/ignition problem was about 3 years ago@ around 130,000 mi.

My symptoms were exactly the same & the restart was immediate. Got so I could drop it in neutral, restart, shift down into D & not miss a beat.