You may have a float with a hole in it that's sunk a bit.

You could also have a nitrocellulose float that's fuel sogged and it sits lower in the fuel thereby raising the float level.
(Common in early Pinto's with their 2 bbl Holley carbs.)

And . . . like dad says the needle valve could be bad.


As far as the start in park and dropping into reverse, the shift linkage could be mis-adjusted.

Coming to a rapid stop with a high float level will many times stall the engine.