Like 88fivepointoh mentioned...what plugs are you running...and what did you gap them at? Just guessing here...cause you haven't relpied back...but did you install platinum plugs? If so, that is most likely your problem. Stick with the basic, non-expensive plugs like NGK or Autolite...not Autocraft. As far as I know Autocraft doesn't make spark plugs?
Was that a typo 88fivepointoh?