I have the same 2000 rpm idle that Mark Schrope had (List posting 7-23-98)
when I switch on my a/c.  Has it been determined that the cause is the idle
stabilizer contol unit (by the right tail light) failing to properly close
on idle?

If I switch off my a/c, the idle stays around 2000 rpm.  If I turn off the
engine and wait a little prior to restarting, the idle returns to a normal
1000 rpm.

When the engine is cold and the a/c is first turned on for the day, the
idle is often at 600 rpm (stall alert!), but after the engine warms up, the
2000 rpm idle occurs.

If the a/c is on, or even after turning off the a/c (as long as the engine
remains on) the idle stays about 2000 rpm.  This behavior is fairly
consistent, but the idle sometimes fluctuates and settles in around 1700
rpm.

The idle stabilizer was replaced last summer (at great expen$e), so I
believe it is working correctly.  There are no vacuum leaks, and the engine
runs fine.

Is there any other reasonable cause beyond the idle stabilizer control
unit?
If this is the prime suspect, is replacement the only option?

TIA for everyone's help.

Budd Premack
86 Syncro, 73 Super
Minneapolis, MN (Land of Sky-Blue Waters)