I don't find any fault with S-Class Gurus advice for the M103 motor. Your car does have the separate fuel pump relay and one fuel pump (unless retrofitted with 2). MAS started with MY90 or thereabouts. Since we don't know the condition of your ignition system, plugs, wires, cap/rotor, ignition coil and crank position sensor are at the top of my list of suggestions. If those turn out to be OK, a weak pump, intermittent FPR, clogged filter or even a collapsed fuel line are possibilities, before getting into the big $$ items like fuel distributor.

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1988 California version 260E (W124)
Anthracite Grey/Palomino
Owned since new and still going strong and smooth
MBCA member

Past Mercedes-Benz:
1986 190E Baby Benz
1967 230 Inherited from mom when she downsized
1959 220S Introduced me to the joys of keepin' 'em goin'

There are only 10 kinds of people in the world--those who understand binary and those who don't