Stalling in gear
First, how's the electrical system? Wiring harness updated? Coils/wires replaced? Not too familiar w/E420s, but I'd start looking at the electrical system. Then if that's all good, check the fuel delivery (fuel pumps, relays, etc).
Reading through this post I'm reminded of my similar experiences with my e420 which has been plagued with this problem, starting at about 25K when new distributors were installed, then again at the 60K service, and twice again since then. My car has been serviced at regular intervals at MB dealers with exception of basic oil changes, and recent cap replacements.
The last time changed to the Beru caps and now with 112K the problem has again returned. MB dealers have never found the cause and it has puzzled many mechanics, who advise "just drive it more, they are meant to be driven." True, but I'm always left with the question why is this an ongoing problem, and where does this moisture/oil film in the caps come from?
Like several of you, my car isn't driven everyday. If I didn't drive it for a few weeks the missing would sometimes take about 20 minutes of highway driving to clear up. As an experiment this summer I tried driving it daily without the problem. But if I missed a couple of consecutive days the missing would return.
Recently I have been in touch with a local e500 owner who praised his local shop/mechanic who has identified the problem, at least in my car-
a faulty (clogged) catalytic converter.


