Is there any think I could do to the tune of my lt1 with a 4l60e to get better gas mileage the engine is mostly stock it just has a cai and a couple of free mods. The car had the maf screen removed when I got it could this make the car run rich? I'm really dissapointed in the mileage the car has been gettins so far the best i can knock down is 19.5 on the highway. Is there any lt1 version of highway mode? All the egr and smog stuff is on the car.