oh my bad, if its electronic ignition,there is a strong possibility,of one of the coils having a crack on the bottom or top allowing moisture to enter it,or it could be internally shorting out,remove the coil pack,inspect all the ends around the hard urethane sealing. look for dark or brownish discoloured spots,also smell the coil,if you smell any burnt electrical smell its possible you got a bad coil pack,this will almost always cause a misfire intermitently.sometimes the cylinder loads up with fuel,then it misfires causing a bang or a ruff running feeling.also check the electrical post ends for corrosion,sand them all down lightly then apply dome dielectric silicone to them and reapply the silicone wire boots.