Hello;  Since October I have watched my  warm idle rise from 880 rpm to
2100 rpm.  I made Idle speed adjustments in an attempt to keep the noise
down.  Conditions finally came together to allow me to be near my nearest
VW wrecker, with enough money in my pocket to afford  a used Idle air
regulator.  I had cleaned mine 4 or 5 times in the last 8 months, so was
conversant with the procedure.
My 13 year old son enjoyed the romp at the wreckers. I asked him to get me
a sunroof hand crank, and sent him out among the wrecks with a screwdriver.
 He enjoyed that so, I told him what to do to remove and replace the idle
air regulator, on the drive home.  After supper he went out with a side
cutter and a new zip-strip and did it.  I went out with the keys to re-set
the idle to get it back to 880.  He sat in the drivers seat and kept the
revs up for me while I did the adjustment.  Real quality time.
The rising idle problem has gone away now, and all's right with the world.
Might tackle the rust spots next.  Larry Carter