im might add, seen many old cars, never once had a coolant system flush clean and replaced.
and found those tubes all packed in orange mudd, zero service cars, do that. like clock work.
when that happens the IAC goes dead. (sticks open ) the hot water to the ISC does nothing to the ISC, but passes heat to the plenum to heat it up.
to see why that happens see my magic, drawing, nobody else has. but in your case if this happens the engine will race and scream hot, even 3000rpm
(assumes 1 failure, not 3) IR gun pointed to IAC and ISC tells you if its happening this bad deal,
http://fixkick.com/Cooling-engine/16v-water-paths2w.JPG
and found those tubes all packed in orange mudd, zero service cars, do that. like clock work.
when that happens the IAC goes dead. (sticks open ) the hot water to the ISC does nothing to the ISC, but passes heat to the plenum to heat it up.
to see why that happens see my magic, drawing, nobody else has. but in your case if this happens the engine will race and scream hot, even 3000rpm
(assumes 1 failure, not 3) IR gun pointed to IAC and ISC tells you if its happening this bad deal,
http://fixkick.com/Cooling-engine/16v-water-paths2w.JPG
http://www.fixkick.com