Several non dealer VW shops have told me my idle stabilizer is no good.
Symptoms are high idle (about 11-1400) when warm, especially after driving
for about fifteen minutes.  I've tried playing with the idle adjusting
screw, with no change.

How do I know if I need an idle stabilizer control valve (which I think is
the valve on top of the engine) versus the control module (behind the right
tail light assembly)?  Are they both simple replacements? Something I can
do myself (I can run a screwdriver, but I'm not much of a mechanic).

Thank...
John
90 syncro westy (2.1l)
SLC, UT