I'm very glad to have found this resource, and I hope someone on the
list can help.

I'm a new owner of an '87 Westy 1/2 camper. PO claims engine is
factory new 40K miles ago, but I'm fairly sure, based on appearances,
that the manifolds and injection system are older, perhaps original.
I've put less than 1,000 miles on it since I bought it, and have done
little work on it, as it's been too snotty out to explore it.

Just recently it began idling way too high as it warms up, building
to probably close to 3,000 RPM over  5-10 minutes from a cold start.
Starts just fine, but as the idle speed builds you can't knock it
back down again with a kick to the accelerator. Sometimes I can pull
up at a light and it will be idling near normal, but will increase as
I sit there. Fortunately, it's a short commute. When it's had time to
come to full operating temperature, which is not every morning this
time of year, the idle has occasionally surged up and down by itself,
up to 3,000 (or so), then falling back to 1,000 or so, then swinging
up again. I don't think that's right, eh?

Bought the Bentley manual, which offers great detail but little of
the working principles of the injection system. (Digifant, if I'm
reading it right.) But because there is an "idle stabilization valve"
and corresponding control unit, it seems appropriate to start there.

So, the questions:
1) has anyone had similar experiences, and how did the troubleshooting go?

2) can anyone explain in 100 words or less what the idle
stabilization valve does? Other Bosch injected vehicles I've had
didn't have one (that I'm aware of.)

3) Should I also buy a Haynes manual for a better description of the
injection system, or is there another that addresses it better. I'd
especially like some kind of troubleshooting flow chart to organize
my thinking around.

4) Should I become immediately familiar with the best VW mechanic I can find?