Hard to start when stopped

I have been fighting this problem for over a year now. It has got better but it still happens, especially during the warm southern summer when it gets in the upper 90s. I have a brand new Edelbrock 600, switched to a cast iron stock 4 barrel manifold, installed a 1/2" wood spacer (made the most improvement of anything so far), replaced the fuel pump, had a plate made to put behind the fuel pump & shield it from the exhaust manifold heat, rerouted my heater hoses over to the inner fender, wrapped the fuel line in heat wrap, took the carb apart & adjusted everything possible. My car no longer strands me but it starts hard every time after it has been sitting 20-45 minutes. It is very frustrating. I am also planning on replacing the starter & battery soon in hopes of maybe getting quicker starts from newer parts. Just chiming in & hopefully helping.