Question - my E300 runs fine except around 55-60 mph, engine turning 2200-2400 rpm. Under conditions when I have my foot lightly on the accelerator (sort of coasting but not really, not accelerating) the engine kind of bucks and stumbles. If I speed up or slow down a little the problem goes away. It drives great at other speeds and rpms.

I suspect this is the range and speed where the a flap is supposed to open, and it's not opening smoothly, or the computer can't make up its mind to have it open or closed. I don't think the car used to do this though. Could this be the problem?

The vacuum transducers are new, and if a flap goes bad I would expect a CEL - recall the '97s know if a flap is open or closed. Or is there something else that folks have experienced like this that had another cause? Just checking. If it's a flap issue I can live with it, I just worry that it might be something else.

Thanks,

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Charlie

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'66 VW 1300 96K miles
'97 E300D 239K miles
'85 300D 203K miles (sold Sep 2012)