[editor-surveyor]

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You probably conquered the “Knock sensor” in the generator by giving it higher octane fuel.

The sensors apply more current to a solenoid that backs off the throttle. (This is only on the ‘high end’ generators.)

[WhoisAlanGreenspan?]

This is an old Craftsman 3000 watt 5.5hp OHV not sure quite how old but it's done the job for me several times now. I kind of doubt it has a knock sensor.

While trying to diagnose the problem, I held the governor rod to the carb steady and the rpm's smoothed out and it didn't stall or rev. Made me wonder if the issue could be in the governor rather than the carb.

The fresh higher octane fuel probably cleaned out some of the garbage trapped in the fuel system is my theory.