jeep just keeps not running right

1998 xj 4.0 4x4 I had no top end power to the point that when I down shifted I would loose power. changed the air filter, that helped a little, ran a half can of sea foam through it, fixed it instantly. now it sounds like it's missing. I do wheel alot, what could be loose, I already checked the vacume lines, they are all in tact so are the plug wires and all the plugs under the hood, I just replaced my o2 sensor. any Ideas will help.

I am having the same problem with my 98, checked the fuel pressure and it was a little low so im going to throw a fuel pump at mine i will let you know what happens.