If you bought a rebuilt distributor,it very well could still be the problem.Not all new internal components are used on the rebuilds.Most people on this forum recommend the Richporter brand NEW distributor.It sells for under 100.00 dollars at Oreillys/etc.Also ground wires are very important to the operation of the ignition system.I.personally, do not have a wiring diagram for the fox bodies for the ground points but maybe someone else reading this post will respond. Good Luck.