cyberunlimited

I have a 1998 SVT Mustang Cobra 4.6. For some reason it's been giving me a check engine light and when I check the codes I get three; P0161, P0136 and P0141. All of these have something to do with the Bank Sensors and I've replaced all 4 of them a few months ago. I noticed that it started after I fueled up last. The check engine light came on and then cleared on its own but later came on again. I checked and the gas cap is tight, just in case this had something to do with it. What can cause this?

Thanks.