Nissan Repair: 88 pathfinder no start, optical light, fuel filter

Question
1988 pathfinder v6 manual. A week ago it started to run very rough and died. I replaced the coil, plugs, wires, cap, rotor and fuel filter. It is getting fuel but It still will not start. I do notice the the spark at the coil end is very weak. I do have full voltage at the plug. I was wondering 2 things could it be the igniter or a bad coil. Unless you can think of something else I need to check.
Thank you in advance

Answer
Bill,

My guess would be the distributor or the ignitor.  But, first check the distributor since they get contaminated with oil.  You say it has a weak spark and that it a usual indication of oil on the optics.  Remove the cap, rotor, rotor post and cover and under the cover you will see a shutter wheel and an optical light and received.  If there is oil it will make for a weak spark and a no start condition.  If it were to run it would run rough.  You could clean up the works and give it a try.  If so, replace the distributor with a rebuilt unit.