I aquired A Technical Bulletin from April 30,1992,It states After driving for an
extended period of time at a constant speed,the vehicle may,on occasion,experience a
deterioation of performance which may be accompanied by a hesitation or surging.
In many cases,after turning off the engine and subsequent re-start or without having
taken any action,the symptoms disappear.These symptoms may not recur for several
weeks or months.
Service:To resolve this condition,wire harness Part no.025 906 302,should be
installed.This harness provides improved signal stabilization.  remove electrical
connector from air flow sensor.   Install wire harness,Part no.025 906 302,between
main harness connector and air flow sensor connector.  This tech bulletin Subject
was Driveability Complaints.Had anyone heard of this harness being used?
David Maguiness wrote:

> With all the discussion about Vanagon highway hesitation/bucking lately, I was
> wondering whether appropriate waterboxer components can be checked routinely,
> possibly as part of a tuneup, to avoid this syndrome before it starts.
>
> In addition, do we have a step-by-step procedure for diagnosing and solving this
> problem if it occurs? I'm asking this because I'm considering returning to a
> Vanagon, and experienced this with both of my former Vanagons, a 1981 L and 1986
> GL.
>
> Thanks in advance for any insight.
>
> David Maguiness
> Indianapolis, Indiana