Many thanks for everyone's input!

I spend a couple of hours troubleshooting the genny on Saturday
morning, and found the culprit. The governor was working properly,
but wasn't returning the throttle to the idle position after the load
was removed. Adjusted the linkage from the governor to the throttle
body did the trick, in association with adjusting the governor to
attain the proper voltage.

I now need to throw a hertz meter on it to finalize the adjustement,
but it now purrs at 120V, settles in at 120V under load, and returns
to 120V when the load is removed.

Now if I can figure out how to keep my A/C from cycling so much, I'll
be in good shape!!