This is the first thing I get people to check when they call complaining of a
high idle.  I would say 75% of 2.1l Vanagons out there have the Throttle
position switch problem.  Some don't have the high idle but this can also
cause problems with hesitation, etc.  And it is the most simple thing in the
world to check.  9 times out of 10 you don't need a switch just an adjustment
or the $6 plastic cam that goes under the throttle valve is worn out.  Always
check this before spending mucho bucks on IS Control Unit or Valve.

Hope this helps,
Ken Wilford
John 3:16
www.vanagain.com
Phone: (856)-765-1583
Fax: (856)-327-2242