sporadic accel - fuel filter?

OK, I've recently (like tonight) come to the conclusion that either

a) my fuel filter is clogged
b) my fuel pump is on it's way out
c) my ECU is toast

I sometimes have good high end power, but not often. I just had a former SVX owner friend of mine drive my car and he says my low end power is unaffected, and I have to agree with him. I think it's the filter. Synopsis:

a) I have good low-end power
b) high end power is f*cked (top speed is now 130mph)
c) smog is fine (so no antifreeze being burned)
d) oil is fine
e) acceleration is mostly flat
f) front main seal is slightly leaking
g) car almost overheated ONCE; radiator cap fixed that

How hard is it to change out the filter? If it's a pain, any problems with moving it further down the fuel line?