1994 Chevrolet Cheyenne info needed

engine runs great cold.. after engine warms up to tempiture while driving shortly after starts to spit and sputter
and pop back.. back fire.. dont want to. run... like its over heating... getting to hot.
then once parked it ildles ok... themostats been replaced... already.... question.. would a bad fuel. pump or bad
radiator cause that...whats your opion...plz out of ideas...
replaced several sensors....temp gauge shows tempiture normal when it acts up....