It could just be a low idle. The 2800 idle screw is notorious for turning do to vibration.
Check the volts of the gen-set, mine would need adjusting a few times a year.
I liked to use. Kill A Watt meter, I could adjust the idle while looking at the meter. It also allows you to check the Hz.
I always tried to keep mine at 120v Usually the gen-set will surge if the idle is too slow, but below a 103 it will shut down with the A/C running. The Hz should be 60.
Also check the altitude adjustment for you elevation.
