Cat doesn't seem clogged, has plenty of power. Airfilter has oil colection, what are the causes, its a new one and has oil collecting, I cleaned the whole airbox... 4cyl ztech, 97 is it a noninterference engine? I think I need a timeingbelt soon. I have new plugs, wires, and what else could I do to improve gas millage? tires are up on air. w/ out ac i get 24 highway and w/ I get 18. The trans threw po1744. Is this why my millage sux? what is avag gas millage for the base 97 gl?