mabey its my 02 sensor?

i recently put a dc sport header on my car, but i couldnt get the old 02 sensor out of the stock manifold. so i put one in i had laying around, and ever since then my car just been drinking fuel. Im not throwing any codes ,but those are the only 2 things i've changed, and i dought its the header. should i change the 02 sensor?

yes... you know your old o2 sensor is good.. try heating it up and back it out carefully...\

gunnmen01