Throwing codes P0171 and P0134

Ok I have a 96 dodge neon highline and it is throwing two codes one is p0171 and the other is p0134 I was driving down the road and it just quit on me all the dash lights turned off and the check engine light was flashing I sat there for a few min like 30 and then it fired right back up with no problem then the next day it did itall over again what can I do I bought the upstream o2 sensor but its still misfire around 3000 rpms