Points based ignitions require setting the point gap. If the points have been used for some time, it is also helpful to clean/file the points' contact faces so they seat squarely against each other. Remove the points from the distributor for filing and evaluation. If you've filed the points down a couple of times, it's probably best to go ahead and replace them. Always install a new condenser when replacing the points. You can find the proper gap setting in the reproduction shop manuals sold by Mustang vendors.