Gas milage problem please help!!

[Ricardo Hincapie]

Hello, but the mass was cleaned, and the car start good. Today i was cheking if the car has any leak, but i can find anithing. Some time ago, the bank 2 or the drive side O2, was give some problems and the CEL was on, but it was cleaned and let ok, and the CEL don´t was on again. when it happened i bought a new one O2 sensor, but i don´t change it, i will change it to see what happen.

 

[Ricardo Hincapie]

Hello again. I check the car, and yes, it has air leak, and it was fixed, but the mileage don´t went back to the top. The car now is 11.8mpg that is a little better. Today i change one O2 sensor, to test if it was bad, but, no, the car go mileage down to 8.7 mpg.
By other way the mechanician tell me that it can be possible if the valves or something on head is bad, but the car don´t spent oil or left somke. I reaaly don´t know what more to do. Thanks for help!!