I just worked on my 94 Onan Emerald Plus.
To clean the carb I ran 4C cleaner through the air filter intake. pumped 4C into the bowl and let it sit for a few hours. Cleaned the idle air passage. Then ran seafoam through it for an hour...from an external tank.
My chock was stuck when it took 45 seconds to start. It acted like a fuel line problem, it was just a dirty choke.
It runs like a champ now.
I installed a PD4645 Converter/Charger.
There is a difference between when the unit is plugged in to home power at 121 volts and when the generator is producing the power.
When the generator is conected the charger goes in to Boost mode.
When the home power is connected the charger goes into Normal mode.
Each senerio was done with no charging for 4 days between each type of connection.
And the generator was run for one hour in the first senerio.
What other than pressing the button to force a certain charge senerio would cause the difference?
Voltage at charging at both senerios was 12.2
My motorhome did the same thing when i first owned it. I could not for the life of me understand how could relax driving these things. Then I checked the tire pressure and found the outside tires each down 20lbs. Brought all tire up to the same lbs and it rides like a dream, Very stable.
Not saying this your problem, good luck.