My 1998 GMC Sierra 5.7 is running rough when it gets hot its stalls then will not start back up until it cools off. problem started on highway when on the throttle truck would break up and would not accelerate only when you would ease on the throttle wot it would not get out of its own way. I replaced fuel pump in Sept. 07. truck when it starts it will idle but breaks up when revved. volt light used to run at 14volts running but now it is two notches down, it also twitches slightly when accessories are on.
I would check fuel pressure first at idle and see if it drops during acceleration when its starts to bog/cut out. If you do not have a fuel pressure gauge, have this test done.
I have had many re works due to aftermarket fuel pumps. You should use a Del-co or Delphi pump. Two reasons the pumps go bad. One is poor manufacturing and two, if you like to run your fuel tank with less than 1/4 of gas then the pumps over heat as the gas is supposed to keep it cool.