Quick Silver 8KW gas generator hiccup

[northern]

Over the past few year the generator will sound like it is stalling then pickup again. Sometimes power to one side or the other will go off during the hiccup. The max load on each side of the generator is 33AMPS. I try to run it around 20AMPS.

Voltage output is correct as I set it as per the manual. The governor oil was changed last year. It did not make any difference. Any idea as to cause and fix?

 

[Little Ducky]

Have you already changed your spark plug(s).

 

[northern]

New plugs, coil and wires.
Seems to be a load issue and type of load. It only happens when I run my watermaker and charger at full 120AMPs but the total amp draw per side is 25.