Thanks Uncle Scotty. I don't think anything is wrong with the O2 sensor(I bought it off a member that said it has about 100mi or less on there); my "old" O2 sensor that came with the swap did something similar, just not as bad; though these are I guess you can say "16-bit" O2 sensors; the scale for them are over a wider range than the newer sensors. I tried using these since the newer ones have a large flange/washer that wouldn't work with the twin-scroll downpipe. I'm assuming the ECU can't physically read how low or high that sensor is outputting. If you say it's the sensor then I'll definitely swap it out ASAP; but I'm assuming I have nothing else to worry about?
Main reason I started this thread was I don't know how much the O2 sensor(s) affect the engine. My background is in Honda so I'm still learning(with the Hondas a bad or missing O2 only affected CL/while driving; so idle, etc. isn't really affected much).