I have been having a similar problem with my caprice. For me, I only have this issue when i drive the car a mile down the street to the coffee shop and shut it off. Of course at this point the car is barely warmed up at about 110 degrees. Once i get back and start the car it barely idles and doesnt respond to feathering the throttle. Only way to get the RPMs up is to floor (which i'm told is what you do if its flooded) until it starts running smooth and clears out the leftover gas. Another thing, on hot days sometimes my car has trouble starting so it might indicate a choke problem?
So basically my guess is your carb is flooding, or its a choke issue, or maybe theres some kind of an air leak (possibly the gasket between the carb and the intake manifold). Another thing, on hot days sometimes my car has trouble starting so it might indicate a choke problem?
Next time it doesnt start try holding the gas to the floor while you crank it over and see if that gets it running...of course don't let the RPMs fly up once it gets going. That stuff is in the car manual if you still have that.