rpinson

About a month of so ago, I started getting codes for the pass side o2 sensor so I figured it was either going bad or already bad. Once I got under the car, I noticed that the band clamp between my headers and exhaust (past the sensor) had broken and come loose which was causing a bad exhaust leak. I bought a new clamp, put everything back together and immediately the o2 sensor codes went away. Since I still needed an extension, I didn't change out the front sensor. Ever since then, though, my gas mileage has been getting worse and worse. Right now, with about 50/50 highway city driving, I get MAYBE 150 miles per tank or so. Could it still be the sensor screwing with my mpg? I don't drive the car hard and 75% of my work commute is on the highway at 65 mph in 6th gear. With gas $4/gal, it's starting to hurt. Any ideas?