Replaced fuel pump

My husband has a 2003 ford f250 5.4 super duty
4x4 truck. He has replace the fuel pump 2x but it
still runs the same. It gets worse going up hills. But
it will run fine and idle fine but taking off or putting
in gear it boggs down and stalls. Has once replace
air filter and fuel filter but still it boggs. He will get
it running ok and then bam it runs like that again.
Now it's been sitting for 6 months rusting, need
help.