[*13*]

I ran all day with Tim & Co, on a nice sunny (70's)day with no problems. As soon as it nears the 80's the "minor" problems occur. A small bump in the idle fixes the problem.
To give a Little history, it was much worse before I drilled a couple sizable holes in the uprights. This is why my thinking has led me to removing a section & adding a different material.
I'm going to think on it a bit more & do a little more testing, based on the suggestions above. Namely, I want to double check the temp of the carburetors.