Before you start changing a bunch of stuff that you may or may not need, you should do a little diagnostics WHILE the problem is occurring. The ambient temp certainly can effect your tune up and the way the engine runs, but to know for sure you need to check. Drive the car on a hot day until it acts up. When it does, stop and take some temp readings of fuel bowls, fuel lines things like that so you have some info. Listen for fuel boiling in the bowls, check the level in the bowls, etc. If you diagnose it correctly you’ll save a bunch of time and money in the long run.