[Uhehner]

After rereading your inputs I would put my money on a weak spark. As the temperature rises and the RPMs increase you need more voltage at the plug for it to fire. This could be wires, plugs, coil, distributor cap or your electronic ignition module if you have one. If you don't then its a Points and Condensor issue. If you have a P&C distributor I would convert it to electronic ignition. Makes all the difference in the world. I'm talking from experience. Ask any guy with an old high performance Corvette. It's not an expensive changeover. Capt. George