It took some effort to get it running, as it had been sitting for quite some months. My diagnosis skills are severely lacking. In narrowing down the problem (and in general, the 95,000 miles indicate a tune-up is in order) I've put new plugs, air filter and fuel filter on board. I also added Sea Foam and 5 gallons of fresh premium gas to the 3/8 tank that has been sitting for almost a year.
Basically, it'll crank over just fine (as long as I keep feeding it with the battery charger!) but fires intermittently. While I had the fuel filter loose, I verified the pump delivers plenty of fuel.
Taking a plug out, I could see I get spark. It almost seemed like the intensity of the spark varied (brightness), though the interval was consistent while cranking it over.
The issue seems to be fuel, but yet appears I have fuel to the engine.
While I was replacing plugs, a plastic spark plug retainer broke, so I made a replacement (left) that looks better than the old brittle one (right):
