Sounds like the fuel filter is plugging up,change it and the air filter. If that don't help,check the cat,it could be clogged up.
My wife says I never listen,at least thats what I think she said.
1993 F150 XLT 4X4,5.8 5 speed
2000 Explorer Sport 4.0
2000 Ranger XLT 3.0