1975 2.0 FI Stock

I have narrowed my RPM hunting problem down to: It only does it under heavy electrical load...i.e., headlights on with turn signals or wipers, brake lights, etc...Very seldom does it hunt during the day, when there is no electrical load...

But what would make it do that...

Need some ideas...

2-OH!

steady, reliable voltage reference is essential to the accurate operation of the ECU.

Hunting at idle is usually an indication that the mixture is too lean. Adjust the knob on the ECU. Check fuel pressure. Check for vacuum leaks. etc.etc

Even though you only see it during high electrical load, it could just be that the mixture is lean, but until the alt puts a small load on the engine it seems to run fine. Once that load is there it starts hunting.
Demick