I've repaired enough power panels over the years because they were blowing out plugs but that is never really an intermittent issue. When they fail they fail all of the time and will always pop plugs until it is fixed. The pulse generator in the panel may be on it's way out.
In my opinion WD40 is as much of a moisture magnet as the glow fuel. I never use the stuff on anything I don't want to rust.
I use Marvel Mystery Air Tool Oil as after-run and never had an issue with it.. Glow engines start up and smoke for a little bit.
The plugs I've had the most luck with lasting the longest are Fox Regular and Miracle plugs.