We have a problem with fast idle and no start when warm on an 89
Cherokee with 4.0L, the Renix multi-port injection, and an automatic.
A search of the web shows this is fairly common, but we seem to have
addressed all of the likely possibilities.

What we've done:
-  replaced and adjusted per factory service manual the TPS
-  replaced the O2 sensor
-  replaced the IAC ("Idle Stepper Motor").
-  cleaned the throttle body, including the IAC port.
-  tested the EGR components
-  tested the coolant temperature sensor per FSM
-  tested the MAP sensor per FSM
-  tested the manifold temperature sensor per the FSM
-  verified grounds
-  searched for manifold pressure leaks (none found, except as noted
below)

Symptoms/history:
-  would idle very high (~1500 rpm) after warming up.  Intermittently,
it would return to normal operation after a period of time.
-  we replaced the TPS and adjusted per the FSM.  Subsequently, idle
speed was variable, but not fast.  One day later, the vehicle would
not restart after being shutdown hot.  Subsequently, we performed the
other tasks outlined above.
-  when the engine cools, it starts okay.  As the engine warms up, the
rpms gradually increase slightly.  About the time antifreeze starts
gurgling in the reservoir (I'm assuming this means the thermostat
opens), the idle rpm increases to 1500 rpm or more (no tach)
-  with the engine idling fast, plugging the IAC port on the top of
the throttle body has little if no effect on RPMs.  Although the
throttle plate is fully closed, pressure on the throttle plate
(butterfly valve) to close it further causes the idle to drop
significantly.  There appear to be very small gaps along the edge of
the plate.
-  I reved the throttle to see if this effected the behavior - it
did.  When the throttle closed, the rpms remained high.  The IAC valve
had opened, and was remaining open.  We shut off the engine, then
attempted restart.  The engine would not start until I plugged the IAC
port.   Once the engine started, the port closed, and idle was
normal.  We shut the engine down, then removed the IAC, cleaned the
valve seat, and replaced the IAC.  The engine would not restart (still
hot).

Any ideas?  I think the CPS is the only remaining sensor, but it is
not clear how that would cause such behavior.

Best regards,
Jon