David, the switch adjustment was the other advice I forgot to mention.
  I have found some switches way out of adjustment and it's amazing the difference correct gap makes.

  Robert
  1982 Westfalia
  1984 GL
  1984 Westfalia
  1986 Westfalia
  1987 Jetta
  1982 Scirocco

David McCallum <dmccom@DIMENSIONAL.COM> wrote:
  Quoting Robert Keezer :

> Did you check the idle switch adjustment? It should click twice, once when at
> full throttle and once returning to closed throttle . With the engine off ,
> you can hear these clicks of the switch. The next step if you hear them is to
> check if the switch is working with a ohm meter.
> The tsting proceedure is shown in the Bentley.
>
> Robert
> 1982 Westfalia

I just went out and checked it, and the switch is functioning properly, but
where the Bentley says the switch should engage between 0.002-0.004 gap at the
idle stop screw, my switch point was between 0.0015 and 0.002. I adjusted it to
switch between 0.003-0.004, and my test drive (motor warm) shows normal
operation of the idle once again!

As I have recently declared victory over this problem, only to have it wrenched
from my grasp, I'll hold off on proclaiming "problem solved", but at this point
I am once again hopeful. The mystery, which I'm certainly willing to ignore if I
have achieved long-term cure of the idle, is why swapping ICMs cured the problem
for my test drive last night. The motor was warm at the beginning of the test,
and I stopped halfway through (motor off) for about 15 minutes, and throughout
the idle behaved as it should.

Fingers crossed and idling at ~900rpm...

Thanks, Robert K, for your input! And to everyone else who has responded to my
dilemma...

David McCallum
'89 Westy - "Boris"

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