My 1989 300ce has the same symptoms as well. I never had a chance to deal with it yet, because my transmission blew. Once I replace the transmission, that is next on my list. I did buy a new Optima battery that I installed. Also, I bought a new distributor cap and I'm going to buy the rotor and wires soon and see if that has an affect. I know my distributor cap that's in the car is not that good.

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1989 300CE Astralsilber/Schwarz
1992 300CE Schwarz/Schwarz