Sammy, the car goes lean on the AFR's. If the fuel was dumping into the carb from the vents I would expect it to go rich. However sometimes stuff doesn't work out how you think so we also done the vent tube thing, still had the issue.
I'm thinking we've had a number of fuel related problems, those being at least: fuel line to small, more squirter needed and this "fuel in bowl control" issue.
Todd, I have a bunch of pretty pictures I can send, here's another one.