Rep Power: 0

I have a ej6 coupe with a freshly rebuilt y7 with about 70 miles on it and it started bogging down bad..I know its not a fast motor but it feels like it definitely has no power when I have my foot all the way down onthe gas it feels like its going nowhere. That's not how it felt on the first few miles. It also idles rough and feels like its going to shut off. When I'm driving it sometimes jerks and its giving me the speed sensor code and the o2 code but that one has been showing since I first bought the car. Can anyone please help me? Thank you in advance.