After tossin g this around a bit it might be a distributer issue? I'm no Nissan expert but intermitant spark can be a lot of differant things? The one good thing about this vintage Nissan is they are preaty plentiful in the bonyard and so are the parts..... Ask me how I know Lol! I just came from ther lOl!! Me and a whole bunch of non english speaking Dudes that is Lol!! I always tell my sons what ever it takes and there is NO such thing is I can't!!!