Driving "like a grandma" should yield you more than 21 mpgs. So that would suggest that something is wrong. And keeping a worn out PCV in place is a poor strategy. Spend the $3 and replace it as it serves an important function. The factory PCV hose is attached the PCV in your picture. You are missing a breather hose and replaced it with that lil filter. And if you have not changed the sparkplugs since buying, get 4 of those as well. Or at least pull them all out and read them to see what is going on inside.