Check the 'between engine and frame' grounds and look for a glass fuse getting warm at the ends.
When you say "check out charging system that is ok", can you tell us what is the voltage output at high rpm?
did you actually change out the distributor with a known good unit? I have known the 'pick up sensor" to cause these sort of problem.
these units almost always get a 'rev up' as they start up, I don't think you are going to fix that part... if you do, let us know how...
and of course, ?you have checked the fluids (coolant and oil), and not just the sensors for them?