So over the past week my GT has developed a slight lope and a definite misfire at idle, part throttle, and cruise, also in between easy shifts it will misfire when dropping RPMs . But there is absolutely no loss of power and the misfire disappears at full throttle. It pulls hard with no hesitation at WOT.
Did a few searches here and found a few posts explaining this is common with o2 sensors going bad. Took it to the dealership and they found a few misfires but said o2 sensors are working perfectly. They changed my fuel filter and said the misfire didn't return. It came back after a few miles!
Cleaned throttle body, sprayed the MAF with MAF cleaner, checked for any vacuum leaks.
Ran Scantool software and STFT is within normal operating range and o2 voltage seems to be too.
But then I see the o2 sensor on one side do this during a misfire for a fraction of a second. The other side doesn't drop off like this and this only happens during a misfire.
Now it's down to COP, spark plugs (4k on current OEM replacement set-followed TSB to the letter), and o2 sensors.
Is this enough information to make an educated guess on my next step or do I need more data? I can screenshot any data needed. Forgive me for being such a n00b to this kind of problem, I've trying hard to research all I can. And thanks for any help, it's frustrating when a dealership says they fixed an issue and it reappears.
EDIT: Just to be absolutely sure, I ran SCT, Scantool, and Torque for any codes and all of them detected no codes this entire time.