Looks like i ran into another problem.

So i went to the shop the other day. Turns out that the reason why i've been losing so much gas mileage (12mpg) is because i have a leak on my passenger side manifold. The guy told me he cant weld the crack because the manifold is cast iron. He suggested that i buy a new manifold (which happens to be a one piece kit connected with the cat) and replace the cracked manifold.

Its quite costly, anyone have any other suggestions?