[jessrayo]

It might be a bad injector but it sure sounds like that O2 sensor to me. If the tune is trying to compensate for one bad injector you will have 3 cylinders running a little rich and one running lean. I can't see the plugs well in that photo but it sure does not look that way to me.

A new 02 sensor is a little more than $100 bucks. That is exactly what happens when I run leaded race gas too long and foul an O2 sensor, it dumps fuel and fouls all the plugs on one bank. Are you running headers? You only need to change the front sensors, back ones should be disabled in the tune. If one is bad you probably want to change both front ones and put another set of fresh plugs in it.

Usualy the sensor goes totally out but yours may just be a little fouled and it is enough that it shows fine on the tune even though it is causing havoc.