Similar situation, my brother's '95 stang, was running fine, then suddenly quit. Rotor turning, but no spark to the plugs. Pulled off the distributor cap and the little pickup magnet was floating around in there. Anyway, had to pull the whole distributor, press the gear off of it to change the little pickup coil. Runs like a champ now and the part cost like $10 but we couldn't figure it out for about 2 weeks.

83 4x4, 3" Lift, 33" Buckshot Mudders