79 20r wont stay running
 

Today I drove the truck maybe a mile down the road and it died. The gas gauge was on empty so I figured it ran out of fuel. Grabbed the gas cans went to store got gas and still the same. I have drove the truck all day today and it has idled and ran flawlessly.i pulled the inline fuel filter to check that the pump was pumping and the filter isnt clogged. All is good there. I have a weber 32/36 carb on it. Only way to keep it running is keep my foot on the gas. This issue came out of the blue! Help!!!!