First off, I have searched for like 3 hours, and cant find anything about what im experiencing. I bought a 1994 civic DX. The car already has a D16Y7 in it. It has a PO6. The car runs alright, but gets only about 20 mpg and seems like its lacking power. I recently got an air/fuel gauge and put it in, and the car runs lean all of the time, and never adjusts. I just put a new o2 sensor in, and Im pretty sure the gauge is right, because it moves around slightly, but not like it should. Since I didnt do the swap myself, I dont know what was done, or wasnt for that matter. If anyone has any idea what is wrong, please let me know.