I was getting a check engine light, (this is what my tuner reads: P013C O2 Sensor 2/2 Slow response- Rich to Lean) so i replaced the O2 sensor on the passenger side after the cat... The check engine light went away for about a week and today while i was driving it popped back on.. I have to drive 1300 miles on Wednesday and im really nervous now. Does anyone know what this could be?? Could it be from my performance setting on my tuner, CAI, HIDS, or exhaust? Please help =[