I had the same problem – However, mine started with a high idle & after fixing the Idle Speed Controller, it became a low idle problem.
Your controller seems to respond to all inputs (temp sensors & impulses).
What I did was adjust the fuel mixture screw on the CIS until the voltage at the Idle Speed Adjust Valve was at 5 +/- 1 volts DC. Then I fine-tuned the Controller by: Using a voltmeter capable of measuring amps.
- Start engine and obtain operating temp
- A/C off and in Park
- Stop engine and ignition switch in Off
- Remove 2-wire connector at Idle Speed Adjuster and pull 1 wire out of connector
- Re-connect the connector minus this 1 wire
- Place meter black lead on free wire & red lead into empty connector slot – completing circuit through the meter – set meter to read 1000+ milliamps (1 amp)
- Start engine and obtain operating temp – if idle goes above 900 rpm, you have a loose connection at meter leads
- A/C off and in Park
- Adjust the CIS mixture until amp reading at Adjuster valve is 1050-1200 milliamps - RPM should be about 650
- Done
Double check operation of idle at PARK – IN Gear – A/C ON