well i did my psi in my tires, cleaned my throttlebody and intake and everything with brake clean, got out a bunch of dirt and oil from when my spark plug came out and blew my valve cover gasket. my next step is going to be replace the air filter. Im still getting about 15mpg average for a tank of gas and wondering how come everyone else is getting 17-20 mpg. my old man is a mechanic and he was saying that with the obd2 (i think it was ) with all the computer controled dyonostics if an o2 sensor was bad the check engine light would come on for sure. I dont have any muffler or exhaust after my cat, i took it all off. so basically it goes from my headers to my cat and ends there. I do fill up at arco and am wondering if that may be why my mileage sucks so much.