Check the ignition timing. If the clamp around the distributor housing gets a little loose, the distributor can turn in the direction of rotation and retard the timing. A late-timed engine won't get out of its own way. A worn rubbing block at the points can also result in late timing and loss of power by letting the point gap close up. If a little dab of grease isn't applied to the distributor cam as the points are installed, the rubbing block can wear out pretty quickly.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!