3.51 false bad o2 sensor reading

[mcdlnwright]

HELP!
I have a 1990 bronco with a 3.51 W. I am having trobble with my C.E light. it keeps going off afetr I drive it for about 10 minutes. It read bad o2 right side so I replaced it.then it read bad egr. replaced it. Bad tps. replaced it. now its saying bad o2 right side again. I was told it could be a vacume or air leak ? all I know is it comes on after about 10 minutes of driving. I can tun the truck off and then back on and it will be gone untill i drive it about another 10 minues. any help would be great