Bjorn:

Call me the coolant temp. sensor crusader.  There are other things that
I can vaguely recall from list history that can cause what you're
experiencing.  But, when that dern temp sensor was bad on my van, aside
from the terrible loss of power after an hour of driving (i.e. telling
the computer the engine was hotter than it really was), just before I
replaced it I had symptoms like yours as well.  I guess that it got to
the point that it was telling the brain the engine was warmed up even
when it was cold.

I'm sure others can point to many probable causes, and they'll probably
be right.  But, that stupid $12 sensor cost me a fortune in replacing
other parts that mechanics thought were the problem, so I'm a bit of an
evangelist when it comes to replacing that thing.

Good Luck,
Tonya
87 Vanagon GL Wolfs
74 S. Beetle