1973 Chevy Caprice car only starts when it wants.

After pushing past 85mi per car would have trouble starting. So I replaced the plugs wires , starter, and battery. The car cranked I went for a test drive made a stop got back in the car it would not crank. everything works horne, lights, radio but the car will not make a sound. I come back a few days later car cranks right up. I drive it home shut it off same thing again, will not crank up not a sound but everythig works. a few days later car cranks right up I stop it and start it stop it and start.Go in the house wait a few hours come ou to take to a shop. car will not crank will not turn over nothing, but everything works. let it sit for a few days it will crank and rides fine but once you shut it off nothing.