I just recently received a few codes on my 2007 F150 5.4 that only pertained to the oxygen sensors. I drove a few days with the check engine light on and had loss of power. I stopped driving and changed oxygen sensors. Drives better, but I have noticed a guttering sound and am getting a cylinder 1 misfire. Is my passenger side cat clogged or is it something beyond that?

 

When was the last time the plugs were changed?

If you think you have a clogged cat, you can test the back pressure using an exhaust back pressure test kit.

 

What were the exact P-codes?