threw some codes after oil change

so i changed my oil 4 days ago. i went with castrol syntec vs. going with the usual synthetic blend. everything was just as smooth as usual, but now i threw two codes P0172 and P0175 (system is running rich on both banks). i don't get how this is possible. but 2 days ago i filled up with the usual 93octane from the 76, and i noticed my stang start having hickups. could this just be some bad gas? i haven't changed out the copper plugs i have for a little over a year now and it's probly time to do that again too, but not sure if that has anything to do with it. any help would be awesome guys.

thanks,
Gus

that's what i was thinking too....paid more money to help it run smoother and gets ALOT more rough! fuel system was cleaned a year ago and i only put 93 in it so i doubt i need to change the filter or clean the injectors again.

yeah....i'm thinking bad gas as well. i know for a fact the MAF isn't dirty nor did i touch the o2 sensor wires. i'll fill up with some BP or Exxon next time!