LA360 Vapor Lock, Heat Soak, OR??
Nothing changed? But what about the fuel? The fuel is boiling at a lower temperature. If you have a dual feed line install a return regulator and get a line that accepts one. You will see a big difference in performance once you do this. If you keep the fuel flowing it doesn't boil.
Your rich issue is the floats not working properly due to the fuel trying to vaporize. It is worse today with the new fuel mixtures then it was a couple years ago and is getting worse. They want these cars off the road. Thank your Democrats!
Here is what I did to correct your same problem.
Before
After V
Remember most of our fuel is imported now. You don't think they are giving us their best do you?