Recently our '90 Carat has developed  problem with idle.  It starts OK,
runs OK for half a minute or so, then the idle oscillates lower and lower,
finally stalling out. It drives OK until I come to a red light , then it
stalls, unless I shift to neutral and keep it revved slightly (auto
transmission).  I have replaced plugs, rotor, cap, O2 sensor.  I checked
the throttle switch, found it wasn't closing on idle, so spent quite some
time getting it adjusted right on the money (no easy feat).  Still idles
the same.  I have checked all of the input into the ECU, everything seems
to be within spec (temp sensors, etc.).

I have found that the idle stabilizes if I turn on the A/C or bridge the
leads to the power steering pump switch, which kicks in the idle
stabilizer.  My question is, is the idle stablizer supposed to function at
all times, with increased function under a load such as A/C, or does it
function only with the increased load.  Mine vibrates whenever the key is
turned on.  Bentley has some diagnostic tests for the idle stabilizer,
which involves measuring amperage when a single connector is connected or
disconnected, can't seem to located this single connector.  It was
supposedly moved in the later models to in front of the air flow meter, but
all I find there is a single into a double connctor.  Is this the one? I
have found that changes in the later models are not always well documented
in Bentley (my stock brakes don't match anything illustrated in Bentley)
I'm hoping someone can give me a hint as to wire colors, type of connector,
etc..  I should point out that I have a CA smog check looming in a month
and a half, so just bridging the connectors isn't really an option, and the
idle stabilizer components (valve and controller) are too expensive to just
replace without knowing they're the problem.  Any ideas, anyone?

Danny Fuller

Sorry if this is a double post, I sent the first to the old address
(vanagon.com not gerry.vanagon.com)