Personally I wouldn't replace it unless you could test and prove that the part was defective. Have you tried different gas stations? Our C230 has always had lots of little quirks. For the little things, it's very often been something seemingly obvious (not mechanical or electrical) that resolved the issue. For example, one day the fuel gauge stopped working. Thoughts started going through my head about replacing the fuel sending unit (is that what that part is called?) and all the labor that goes with it. I starting thinking back to what I had done differently right before the problem started. Oh yea I had put el cheepo discount store gas in the tank. Went and topped off with Exxon or Amoco and bingo the problem was fixed and it's never come back. That was like four or five years ago. Another time was the CE light. Got the codes and couldn’t figure it out for the life of me (keep in mind I’ve been through the MAS twice and know what that’s all about). Starting thinking about stupid things that would mess up the fuel pressure and delivery. I took off the gas cap and started poking around. I looked real closely at the gas cap itself and saw that the rubber grommet was starting to dry out and crack. Switched the gas tank cap from the E class wagon to the C230. Problem solved with an $8.00 gas tank cap. I don’t have any ideas for you, but I’d bet it’s something lame that’s being overlooked.

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Michael

1988 300 SL (5 Speed)
1994 E320 Wagon
1997 C230