Jkazzoun,

I had similar symptoms with '95 E420 - bogging down during acceleration - symptoms got worse over time. While I don't assume your problem is same as mine was...the solution was easy & inexpensive, so you might want to check.

Fuel Filter. Even though pressure was within spec during idle - measured at fuel rail. Upon acceleration, insufficient "flow" getting to the rail & thus injectors. I even picked up a few codes (I seem to remember...maybe wrong about this though) that led me astray in my diagnosing process.

Anyway, same sypmtoms you're describing. I replaced the fuel filter...and it was like a new car. Interestingly, the filter wasn't old - a baffle/plate inside had dislodged partially blocking the outlet path.

You may have a fuel line restriction. Not necessarily at the filter.

Can you check fuel pressure at the rail - both at idle and then upon acceleration?

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Syntax26

1995 MB E420 (lowered)
1989 MB 300SE (sold to brother)
1975 MB 280 (sold)
One damn fine jacked-up golf cart