[Curtis in MA]

I guess I would follow a few clues.
First, what would not work when the engine is cold that would when it is warm?
But since your in SoCal that might not help.
Second, what would stick when not used overnight but loosen up after started?
Maybe a throttle linkage or valve. But since you rebuilt the carburetor that might not help.
Let someone else start the car while you watch the throttle and carburetor.