error code 43 91 prelude

ok so i just got this prelude si alb 2.1 a cpl months ago and am in the process of getting it tuned up and all that ... runs great but the gas mileage isnt all it should be.... im gettin an error code 43 which i find online is a fuel system error... so i changed the fuel filter hoping that would make it go away cause the only time it really pops up is when im getting on it fairly hard.... like when accelerating onto the interstate....well htat cured it for awhile but then came back again.... is my fuel pump goin out .... or should i check out the fuel sending unit ? also how hard is it to change the fuel pump? or is the problem most likely somewhere else... im lost so hopefully someone here will be able to help me out some.. thanks in advance ....

If I were you, I'd change the fuel pump. It's not that hard. And if that doesn't do it, check your injectors, if it's not carburated.