Heat and humidity are more likely to affect the high voltage electrical components of your brick than the fuel system.

How old are your plugs, plug wires, coil wire, and distributor?

Have someone try to start your car on a hot, humid NIGHT while you look under the hood for arcing. Don,t touch anything!

You might improve the situation by cleaning the electrical items mentioned. I use WD-40 and a rag, although I understand that someone puts them in the dishwasher.
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3 8s & 2 7s 740,000 miles total