Is it fuel filter or something else??

I put 13.4 gallons into my tank to make it full, I reset the trip before I left the
gas station.  I drove 152.6 miles and it now sits two needle lengths away
from E.  It used to get 26mpg, that's what the previous owner told me (family
friend).  My dad thinks it could be the fuel filter.  I'm recovering from a hernia
surgery, so I can't really go out and troubleshoot.  Just would like some ideas
for when I am able to get my dad or someone to come over and do the work
for me. Thank you for any advice in advance.