I've been working for a long time to fix a problematic idle in my 1982 k-jet MPG. The IAC and throttle switch are both working well, as is the fuel system, as far as I can tell. I think I have kept vacuum leaks at a minimum.

I believe the problem is electrical, having to do with the ECU which controls the CIS. I know this ECU takes input from the TPS, the A/C, and the ignition coil, as well as a temperature sensor. That's where I think the problem lies. See, the idle is fine before the engine gets hot. Once it's hot, it's as if the ECU tries decides what it's going to do (when I depress the clutch), but in the end it's not opening the valve enough--the car almost stalls, sometimes does (when you've been driving for 30 min or more). If it doesn't stall, the ECU hunts around for a better setting, and sometimes finds it. Note: none of this occurs with the AC on. It's as if the AC signal to the ECU tells it to override whatever is causing the problem.

So I think the problem could be the temp sensor, can someone explain where it is? And where does the wiring go--I'd like to inspect it. Is there a way I can test this temp sensor?

Any other suggestions about what's causing this problem?