Misfire in cylinder 3, P0420 code
 

I have an 2023 S that started stuttering/sputtering/ acting like it wanted to stall all of sudden when I was be easing on the gas or begin acceleration, not hard acceleration either. This started happening when I unplugged my AFM disabler while the car was on, I unplugged it since I was going on an long distance drive and wanted to save on some gas but Im guessing now I shouldn't unplug it at all unless I have it sitting for an extended period. A shop is telling me its a misfire in cylinder 3 and they did not see an leak either. Anyone have any suggestions? (currently at 33k miles btw, and I have unplugged my afm disabler before n this never happens, I just usual do it with the car off n did it with it on this time so wondering if that could have caused the issue possibly, i do have a sec cat delete too but ive had it for a while now n never had this issue:pout:)
:pout:

Did you pull the battery cable off to reset the ECU? If it was caused by you pulling the AFM disabler while it was running, it may resolve it. Hopefully you don't have a bad lifter.

No I haven’t, im not 100% sire it was caused by that but I just know thats when I noticed it, so should I still try to reset the ECU? If so where is it located for me to do so and will it reset anything else that I may need to worry about?

You now have an exhaust leak large enough to give you the P0420 code. Most likely from the exhaust work. May have started as a small leak, but now it's bigger.
https://www.camaro6.com/forums/showt...=600204&page=2

Mechanic said they didnt see an exhaust leak though, I will have it looked at again though

You probably need an exhaust shop to hook up a smoker to find any small leaks.
It would also be useful to look over many of the secondary cat delete threads here. I am not sure what they do with the downstream O2 sensor, but I suspect it may get replaced with a cheater plug that fools the ECU so you never get a code.
https://www.youtube.com/watch?v=qHD7T7EhuzI

In your trunk above the passenger side wheel well is your battery. Just pull the cables off the battery for several minutes and it will reset things. You might lose things like radio station presets, clock settings, etc. But it won't hurt anything to try and it's free.