Mine is a 1982 Vanagon, originally diesel with a conversion to a rabbit
engine from about 1985.

Do these symptoms ring a familiar bell to someone knowledgeable on this
list?

Last Wednesday I took off at 3 PM intending to drive about 500 miles.  It
was about 100 degrees out.  After a short time, I noticed a frequent,
partial loss of power, much as if I had suddenly backed my foot partway off
the accelerator.  When I had to stop, the engine died unless I kept the
engine RPM's up.  Both problems became worse, so I limped my way back 35
miles to my mechanic right at quitting time.  I also noticed that when
stopped and holding the engine above normal idle (to avoid stalling) that I
could hear the fuel pump cycling every few seconds between high and low rpm.
When it reached the low end of the cycle, the engine would almost stall, and
then pick up again as the fuel pump took off.

I suspected a bad fuel pump but my mechanic wasn't convinced it was so
simple and I'm not a mechanic.  The next day was cooler and he has so far
not been able to repeat the problem.

A VW mechanic friend told me about a static electricity problem with this
engine series that might cause such symptoms and could be corrected with
some kind of an adaptor.  I found a reference to this problem in the
archives, although not much detail.  My friend also thought that the high
temperatures could be causing vapor lock.  If it's that, I don't know how to
confirm or resolve it.

I should say that I first noticed this unsteady power problem more than a
month ago, but then it was infrequent and subtle, so I let it go.  But last
Wednesday it wasn't sure I was going to be able to make it home, never mind
my intended trip across the hot plains of Eastern Colorado and Kansas.

I appreciate any help.

Thanks,
Paul in Fort Collins