More Strange 5KCS Stalling/Hard Start

[Steve Sherman <spsherm@ibm.net>]

Thanks for all the advice on the stalling under idle and hard starting my
wife's 86 5KTQW is experiencing...but I still am searching for the cause
(and a few more ideas)

I've checked for the usual, no vacuum leaks that I can spot.  And wiggling
hoses doesn't seem to effect (create/cure) the problem.  I also cleaned out
the ISV and checked it contacts and its plug's contacts and wires.

I've driven the car for a few days, and seem to have narrowed the problem
down some.  The stalling only seems to occur when at idle, or when
decellerating to idle.  Sometimes it will lug along at 400 rpm for a while,
but it eventally dies.  It appears to be worse in warm weather (60+F) or
when the engine is hot.  When it's happenning it seems it can be hard to
start/restart the engine after a stall, but flooring the gas pedal seems to
work.  Likewise gently pushing on the gas to keep rpms at 12-1500 keeps it
from dying.  And of course things are fine at hi rpms.  In short it's the
"old dies at idle problem."

I can CAUSE the problem (or at least one with the same symptoms)...  When
the engine is idling OK, if I quickly unplug then replug the ISV, the car
will go into the same mode as  the problem, idle drops to 400rpm and then
stalls.  Even with the connector back on (I only disconnect it for <1sec)
idle never recovers....

Can anyone out there who is familiar with CIS tell me what (if anything)
this may mean for the real problem.  What mode does the CIS go into when I
momentarily disconnect the ISV?  What might cause that in "real life" and be
worse when warm?  (I have checked for damaged wires, and don't see any at
the ISV end.  I will check out the ISV controller, somewhere under the dash
too...).

Other suggestions welcomed too.

TIA