Why would you sell your PS4 and go back to PS3? The production of PS3 games will be discontinued very soon, most of the new games are already next-gen only. If I were you, I'd save enough money to buy a decent PC, when you are already unhappy with the PS4.
No point in downgrading. If you're dead set on selling it, might as well get the PC. Atleast with that you'll be able to play newly released games, instead of being stuck playing last gen games on a ps3.