I've had these codes for a couple of months now. Can I fix these myself (novice) or do I need help. I saw the technical post on this but was a little over my head. Part 2 of my question is that my gas mileage seems to be in the 13city range - is this being affected by the codes? I was expecting to get around 15mpg but i'm getting like 200 miles on a tank which stinks. any advice would be great.

Please, anybody, should I fix this, can I fix myself?