Most of the bases have been covered by the above suggestions. Have you tried checking for vacuum leaks by using an unlit Propane torch around the intake manifold gasket for the center port in the cylinder head? If the engine smooths out or speeds up, you've found the problem. It would be hard to run fast enough to give me a Pertronix system, but some guys love the things. If you have a regular distributor with points the next step would be to swap it in there temporarily and see if the problem still exists.
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!