You might want to check on the starting capacitor's It may run at 670 but the jump in voltage will trip the breaker if it isnt set up correct with the Genny and Distance is everything ! How long the run is from the AC to the genny you will lose amps
They only start once and then never cut off. LOL. Look at my address.
One is about 20 feet and the other one was about 30 feet.
The thing I saw the most of what you describe is when I washed clothes. The washer made a noticible drop in starting the wash and then the spin cycle.