Hi my 1987, 190E 2.3 16 value, has some sort of problem, it is sometimes hard to start; is is fuel injected; I have replaced the fuel pump, fuel filter, plugs, & wires, rotor button, distrubtor cap, it ran great for awhile, but then it became hard to start, & would sometimes, dies after starting & running; this was always a cold start problem; thanks any help would be greatly appreciated..Wilford

Check the fuel pressure regulator, check valve and accumulator.

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1989 300CE

Since you say it's a cold start issue, before you spend money on other parts, have you checked your engine's compression in each cylinder? The 2.3-16 is very sensitive to valve train neglect, particularly the valve adjustments via the bucket shims. When out of spec, the exhaust valves can leak. When was the last time those 16 shims were inspected and adjusted?