how can i fix my 94 jeep wrangler?

it's a 94 jeep wrangler, manual. it works fine in idle, but when you get above 2500 it ends up sputtering and loosing all horsepower.. it's quite difficult to get it out of 2nd gear. it dies if i go up hills, either that or the check engine light comes on and i can't get it to go above 10mph. i've replaced the fuel filter, and it didn't help, i replaced the MAP sensor, didn't help, i put at least 3 cans of seafoam in the gas tank in hope that i would flush it out. it seems to be being starved of fuel. but i don't know if it's actually anything to do w/ the fuel line or not. i'm trying to avoid having to replace the fuel pump, b/c i don't want to put that kind of money into it if that's not really the problem at all and i'm thinking about the spark plugs next.... help??