Stutter at idle no code

Year: 2008 Make: Mazda Model: speed3
Mileage: 140,000
Location: WA
Concern:
I have noticed a stutter or rough idle that just started… when it happens feel like a misfire but my afr jumps to 15.2 and then go back until it happens again open loop seems to run fine but as soon as it’s in closed loop it comes back. I am thinking vac leak but I sprayed everything with brake clean, nothing. exhaust leak? I did notice my o2 b1s1 is turning on and off when I hooked my scanner to it.
Is that normal?
DTC’s: Nothing new since this started
Mods: hpfp, 3” intake and turbo inlet, catless 3.5” turbo back exhaust. Nothing crazy

ECU/Tuning software: access port v3 tuned by stratified

Recent repairs: new stock size turbo ran great after install then 3 days later this started. No leaks that I can see, I reinstalled all the intake pipes to make sure they were good.

Let me know your thoughts thanks everyone.

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