Hey, I hear you on the idle troubles....mine a little different.

One question:  you mentioned that you cleaned out the idle valve while you
were in there.....would a dirty valve be the possible cause for a
sketchy/gummed valve switch? Just curious if you or the list knows this.

When I had my first idle troubles, I did the same...replaced the idle
stabilizer  & 02 snsr.....and then I had the hi rpm' situation in park, which
really stank.  Turns out I had two cracked vacuum hoses under the air filter
housing.  Boy what a difference.  As I went around and checked every little
hose, it only got better.  Also, I would think you should trace all the wires
to the places that the ECU's wire harness goes..every single one....while
you're at it with all the vacuum lines of course.   This would encompass
everything from the 02 sensor to the fuel injectors in the engine
compartments fuel system.  Just start at the ECU and follow the happy little
trail.  :-) Replace any wires that are sketchy.  Takes a while, but it sure
must give you some insight into the spinal cord (ECU) of your motor.  The
respiratory system is of course would be those vacuum lines.   ;-\     I'm
going to go through this entire procedure myself this weekend.

In a vehicle that is so tough to attain a perfectly splendid idle, etc, it
seems to me that starting at the brain of things and tracing them to their
finite little ends might be the only way to comb everything out for real.
That is.....if your a budding VW addict such as myself.

Good luck
Dustin
'85 Passenger 1.9 - "Chuba"