>
> For some reason,
> COMPRESSION BRAKING seems to throw something out of whack.
>
> Is this a clue? Or a red herring? If it's a real clue, where would you
> look?
>

FWIW, compression braking is generally only found on diesel trucks. Theres a
valve flap in the exhaust manifold they close and the pistons have to
compress air against that on the exhaust stroke. On gasoline engines it's
actually VACUUM braking, i.e. the pistons are pulling against a vacuum in
the intake tract. The big air valve in the throttle body provides the seal
when pressure is taken off the gas pedal. Dunno what might be the problem
after pulling a big vacuum for a while, but it might be worth looking for
collapsed or rotten vacuum lines.

--
John Bange
'90 Vanagon - "Geldsauger"