I have a '98 Taurus that is sucking gas like a Slurpee. A while ago, it threw a "system too lean bank 1" code. The guy at the parts store said it was probably the 02 sensor. So I cancelled the code and went on my way. I got another sensor at the junk yard and finally got around to putting it in, but it still sucks gas. My question is: do I have to re-program something, or could the sensor be bad?