The ecu does get a signal from the temp signal. As the engine gets hotter it increases the fuel.
It almost sounds like an injector issue. Didn't you say you had issues with rat chewing up wiring?
You can check the injector cycling by turning the ignition on, pulling the dizzy out and spinning the dizzy gear to verify the camshaft position sensor along with the injector function.
Next guess is a vacuum leak issue. Lol. I had a similar thing happen. Engine runs fine when cold it once it warms up it misses and stumbles. I found out that one of the vacuum hose going to the carbon canister was not hooked up.
But this doesn't explain the intermittent issue.