Honda 2000 running errantly - Altitude issue?

Lately, what I have been doing, at home, is every Saturday, when all the towels get washed at home, I fire up the little Honda Eu1000i, and plug the washing machine into into it for a 45 to 50 minute cycle to run some gas through it and do the laundry. This is week 3 or 4, and the little Honda is running good now, no searching for rpms. 1 oz of Seafoam added to the 1/2 gallon tank of fuel the Eu1000i holds.

washing machine is a high efficiency model, and the electric motor never hits full load on the generator at start up, it is rather gentle, the start up, probably due to the electronics in the washing machine unit.