Hi all--

I just replaced my 84 Vanagon's blown 1.9L with a Boston Bob 2.1L rebuild,
and am having a small problem.  The core, starter, and throttle body are of
the 2.1 variety, but I used the coolant system, exhaust, and Digijet system
from the 1.9L.

When the engine is not loaded but also not at idle, it can stutter and
sometimes get into a resonant mode where the whole car starts shaking and I
have to push in the clutch.  The problem is worst when you're just puttering
around town at a constant 20mph or so--you have to watch it like a hawk so
you can push in the clutch at the first signs of shaking to keep your
passengers from getting shaken around.

The engine performs beautifully at idle, when accelerating, or when at
highway speeds high enough to keep it under significant drag load.  It
happens at any engine temperature, and the clutch and transmission are new.

A recent ebay ad for an air flow meter implied that it could cause a problem
like mine--that the spring/damping chamber can wear out and cause it to
flutter.  Mileage is worse than my 1.9L (~17 instead of ~21 for my driving
style), but Greg's Auto Repair (Natick, MA) set it up and said the emissions
are extremely low.

Anyone have any advice?

Thanks----------------Andy