Backwards fuel filter ?

okay, I have a 1989 dodge dakota 2wd, v6 TBI. I put a new fuel filter on it and it seems as though around the same time i put it on, i started getting worse gas mileage. i used to get about 14.3 mpg and 270 per tank. now im just getting 230 or 225 per tank. I dont know if a backwards fuel filter will do that or not. please help. thanks