I have a 1992 ford small V8 that the distributor and rotor have burned out twice. I performed a tune up last year (replaced plugs, wires, new cap and button) and it will run good for a while and then start missing which is the first sign that the distributor contacts are burning up. Any ideas on what is causing the problem because my mechanic and I are stumped,

 

What kind of coil do you have? What are your plugs gapped at?

 

what are the KVs on the secondary side, any aftermarket performance ignition coil as PKRWUD asked and is the sprk plug gap at spec and not way open. is it burning it or could the dist shft bushings be bad and the rotor smacking the cap. pull the dist. and check, may be able to tell without removing it most cases if it will hit the cap but that usually give more drivability symptoms