Chevy S-10 2001 repair question need some help?

Friends chevy S-10 is having a problem acts like a fuel delivery problem can hear the fuel pump come on and have changed the fuel filter didn't notice allot of trash in it and replaced throttle position sensor when Driving down the road and press the gas all the way down as if passing wants to try and stall out or it will go to high rpm and go slow when in idle sometimes runs fine or will stutter when u try to press the gas will try to stall out back fire on occasions he did run out of gas a few times so was thinking do a fuel treatment please help if can if u need more info i will update and ty