'87 4KQ idle blip is fixed

[Russ Maki <rinard@execpc.com>]

Hello again list!
Thanks to all who offered advice on my car (the '87 4KQ with the
8000-rpm idle :-P).
Actually, the lumpy idle was caused by a bad wire from terminal No. 1 of
the idle stabilizer valve connector to terminal 14 of the control unit.
The air-conditioning circuit also was getting in on the act somehow,
which was where the repeated, regular blip (switching effect) was coming
from. I didn't quite grasp the physics involved here; I gave up on the
problem last week and turned it over to a mechanic, and that's what he
told me. He finally tracked it all down after about 5 hours of diagnosis
(not all of which I paid for, happily).
The repair: new line from the ISV to the control unit and disconnection
of the wiring to the already non-functional AC. The AC harness, the
mechanic suggests, probably has some internal squirrels of its own.
BTW, my last resort in dealing with this problem was going to be a kluge
that somebody sells in the BMWCCA classifieds: a manual idle control
valve. It plugs into the intake in place of the ISV and regulates vacuum
with adjustment by thumbwheel control.  Has anybody tried such a device?
Just curious.
Russ Maki
Idle back to normal --
850 rpm