These symptoms sound like a fuel pump relay to me, although that does not explain the problems at low fuel level particularly well.

The tank IS vented, find the vent line underneath and unplug it. Typcially a vented cap is bought a McParts to replace a lost cap by someone who doesn't know MB doesn't use vented caps (no one does these days, but McParts still carry them).

You should also replace the OVP relay if you have not, it will also do this -- engine looses mixture control and stalls, but everything resets when you shut it off and restart.

I would also check the intake system for air leaks after the air flow meter flap -- this can also give you fits.

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!