Throttle position sensor fluctuating at WOT

Hey guys, I'm new here and just have a question. I have a 13 Buick Verano turbo that was tuned by BNR and I have lately had an issue with it stumbling/ hesitating at or near WOT. I logged some data on this yesterday and noticed my TPS percentage fluctuating from steady at 84.7% down to 72% when I know I was at WOT. Is this normal, or is my tps going bad. I know the 84 is normal, but shouldn't it be staying there until I lift? I've noticed extremely high idle occasionally as well during cold start. Like 2000 to 2500.

Immediate thought is how old are the plugs and the coils? High rpm misfire is can be related to either one of those. Old plugs can increase the gap and get spark blowout or just misfire or bad coils can misfire. Look at your log and misfire for each cylinder to see if what cylinder the misfire is happening. Since the Verano uses individual ignition coils you can just do a coil swap from one cylinder to another to determine if it's the coil.