On my 78 F-250 4X4 with a 351M. The contacts on the dist cap seem to foul very quickly. The spark plugs do not foul, and everything else runs smoothly. The performance drops off noticably when the dist contacts foul.

What could be causing this, and is there a remedy to fix it?

 

you must be buying the ten dollar wells aluminum contact caps, try a quality cap with copper contacts, gonna run ya about 24 bucks