Okay I change the Gasket that goes from the carburetor to the intake got rid of 1 spacer and I still have the same problem if you leave the car sit for about five hours it will start right up but if you are running it and shut it off then come back 30 minutes later it has a tough time starting. I had a friend come over and see this happen and he told me to install an Electric fuel pump because it is Vaporizing and it is taking time for the gas to get to the carburetor, I guess it is boiling the gas into vapor because it is so hot so I have air in the line instead of gas so it takes some time to get the gas back to the Carburetor .
Think about what you just said. It is boiling the gas off and is hard to start 30 minutes later. BUT, if you let it sit for 5 hours, it will start up. If the engine/fuel pump is not pumping the gas to the carb, how does the carb fill up on its own 5 hours later so it will fire right up?
Pontiacs can become hard to start when hot. The cam selection can do this. Too much cylinder pressure being built up and when the engine is hot, the starter has to work harder to kick it over. It could also be a weak starter, low battery charge, corroded battery cables, or even some of those aftermarket store bought battery cables which are really too small in wire gauge to give the starter a good solid 12 volts/maximum battery AMPS to spin it over.
Next could be timing. Timing can play a big role in how the engine fires up when hot. Have you played around with the timing to see if it fires up better when hot at different settings? Maybe timing is too far advanced or distributor issues. Could even be a heat soaked coil or some other electrical situation that needs to be checked.
Check all rubber lines & connections for cracks or deterioration - front and back at the gas tank. Had bad starting problems with my '73 Fury. Turned out to be dried out rubber hoses that had become hard as rock and the replacement type spring clamps that hold the hoses to the fuel line. The spring clamps are fine when the rubber is new & soft, but when they get hard, the spring clamps can't clamp tight enough. The rubber lines were somewhat loose and sloppy and when I grabbed one to check, I had gas pouring into my hand. No leaking at all from the line, but when I moved it around, it leaked pretty good. So the gas line was both sucking in air at times and probably pushing some of it out under heat/vapor pressure. Once I installed new rubber lines, band clamps, and a filter, problem solved. Car fires right up every time I stop and re-start. Now I still have to pump the gas a few times to get it to start when it sits a few days or weeks, but I know the gas evaporates sitting - and Plymouth's run hot under the hood.
The ethanol gas is indeed a big problem and it could be heat soak vaporizing the fuel, but it may not be. The electric fuel pump can work as my brother added one to his Mopar which would pitch a starting fit when he shut it down hot and then tried to fire it back up. BUT, it also took a little bit to get it fired up even when it cooled down - just more cranking of the engine than should be. Now he says it starts right up and he does not have the hard starting issues when it is hot and he shuts it down and then hops back in it 5 minutes later.
He also has the same issue with his '57 Caddy and it will not re-start on really hot days unless he lets it sit and cool down - which is a real pain. He has even gone so far as pouring cold water on the fuel lines that run along the engine to get it to fire up. Those older cars don't have big fuel pressures coming off the fuel pump to begin with, so he is adding an electric fuel pump to that car, as well as plugging off the exhaust heat crossover under the carb and installing an insulated carb gasket.
So, could be the gas or you may have other issues compounding the problem.