It's not just Vanagon transmissions, I think pretty much any automatic will do that to some degree or another.  The newer ones with some computer smarts might be a bit better about it... but I have to do the same thing with the transmission in my old Mercedes 300D.... around town I keep it in "S" (which locks out the 4th gear) instead of "D" otherwise I'm kicking in and out of 4th constantly.  Just because it's an automatic doesn't mean you can't use the gear selector to override it.

Allan

On Wed, 26 Aug 2009 10:04 -0400, "Mike Collum" <collum@MYFAIRPOINT.NET> wrote:
> Marc Perdue wrote:
>    The damn transmission keeps bouncing back and forth as my
> > speed varies between 45 and 55, trying to haul my butt over the
> > mountain.
>
>
> When I'm driving my '84 7 pass automatic in the mountains (wasserboxer
> engine), I just manually downshift one gear and leave it there until I'm
> on more of a level plane.  It works for me and is certainly better than
> the frequent up/down shifts that the system would provide on its own.
>
> Mike
> '84 GL 7 pass auto
> '85 GL Westy 4 spd
> '84 Westy 4 spd
> '84 Westy parts