Why does my 1931 Ford Model A backfire and die after driving 5 miles?

Check the carb., make sure it is clean. If it not clean, blow it out really good, dip in in a bucket of gasoline, let sit to dry then blow out again. Check spark plugs, clean, change if neccesary. Drain gas if unsure how old it is. Very easy to drain gas, unscrew from firewall, and turn gas switch on with hose connected to it to drain. More than likey, bad gas and/or spark plugs need to be cleaned/changed...