I originally thought it was an intermittent fuel flow problem. However I discovered after setting outside over night that it ran really poorly at first (worse under load) then gradually improved over the next 10-20 min as it warmed up. This repeated after setting out a second night. Hooked a timing light up to one of the plug wires and it looks whenever it misses/surges there's no spark (light doesn't flash) I've put my hand on the plug wires when it was running badly to feel if there is any leakage and couldn't feel any. There was a tune up before mowing season with new cap, rotor, points and condenser. I plan to replace the plug wires as they are old but don't think this is the problem. To recap - runs poorly under at load after setting all night. After 15 min or so runs good with only an occasional hick up. Seems like it may be moisture related. Thoughts?