This might sound odd but bear with me.. Hook a spark plug wire to a plug... Ground plug and see if the plug is sparking..I once had a whole set of plugs not fire on a friends car.. Ran fine pulling in.. Few hours later nothing.. Had spark coming from coil had fuel but nothing.. Plugs were all carbon fouled which caused them to short out... If you have spark at coil but not at plug either it's the plugs or the distributor cap