5kcstq idle problems

[Ben Swann]

[Car: 86 5kcstq.

Symtoms: Car has been very hard when it is warm for about a week.  Over the
weekend I replaced a few vacume hoses, this helped the hard start problem.
Car started Ok(not great but OK) on Sunday and Monday.  Today the hard
start
comes back with a new problem.  The idle is surging between 1100 and 1600
RPMS.  I looked at the duty cycle of the frequancy valve to check the
mixture and noticed that mixture would vary from 35 to 65 in a constant
movement(not the normal 5 or so degree variation that is normal) and then
shoot down to 35 and start the process over again.  The movement is in
phase
with the idle and takes about 2 sec.

Tried: Unplugging the idle stabilizer has no effect. unplugging the O2
sensor no effect.  Looked for vacume leaks none found, does not gurentee
that there are none.

Ideas]

Yes - unplugging the ISV and experiencing no change confirms - ISV is bad.
 You may have other things mixed in too.

A wagon I recently aquired, same symptoms, seemed to eat ISVs for lunch -
replacing used with used did not always make a permanant fix, but it was
indeed the ISV, in the end.  I now have a better condition but still used
ISV in the car and it runs fine.

Ben