Hi, if you change the strings and it still sounds horrid, it's possible the the bridge needs to be ' Set up '
The Symptons are : it will tune up OK and chords at the lower end will sound allright, but the further you climb up the neck the worse it will sound.
A reputable Music store will re - adjust the bridge for a small fee, or someone handy with an Electronic tuner will be able to sort it.
Fenders - I love um