Let's look at the other end of the fuel system. Trash in the line to the carb could migrate to the needle seat and easily stop flow during an uphill acceleration, then fall out during idle when the float closes. Check the carb for trash in the inlet well. Do you have a filter at the carb?

Just grasping at straws.

~~ Jethro
1954 3100
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1951 3100 (gone) / 1956 4400 (still in the neighborhood) / 1957 6400 with dump body (retired) / 1959 3100 panel (in the woods junked) / 1978 Custom Deluxe K10 / 1993 S-10 4.3 / 2004 Chevy Crew Cab / 1945 John Deere H / 1952 John Deere B / 1966 John Deere 2510 / 1967 John Deere 1020