so i've been doing alot of work to my truck the past few months. i've fixed a bunch of things i half assd when i put the engine in. when i put the 2rz in i made my own harness basically, wired in all my own relays, push button start, switched after market fuel pump. basically if it wasn't necessary i didn't hook it up, now im wondering if the reason i have so little power is because i have no o2 sensors. i really just trying to ask is putting an o2 sensor in gonna make a dramatic difference. im not putting a cat in it, so i would just be running the sensor closer to the manifold.