79,
We've talked about a similar problem recently. It may be the coil breaking down when hot, by changing the condenser, you're actually letting the coil cool down, and it will run again....................See if you can get the coil load tested, or replace it with a known good one.............An altervative would be to install a Dyna S, or Mallory points eliminator set-up. Set it, and forget it.