HELP! Slant 6 just doesn't want to go!

Does it happen only when hot outside? Slants have a common problem with the fuel boiling in the supply line to the carb, though doesn't usually bother our Canadian brothers. There are several fixes w/ photos here. If you get a clear fuel filter, you can see when it goes to vapor. Don't be alarmed if you see some air or vapor in the fuel filter since that seems to be common. Some people have installed a filter w/ a vapor return port on the top and run a tube back to the gas tank, but that probably isn't necessary to fix the problem.