I have a 2017 6.2l 1500 Sierra with 1 7/8 ARH headers with ARH 200 cell high flow cats. I have a CEL throwing codes P0420, P0430, P050D. Upstream o2 sensors are disconnected shop did the tune and I had no CEL or issues untill now. At idle both downstream o2 sensors are around 0.7v and constantly dropping to 0.1v once a second or two consistent with the rough idle. Any ideas? If anyone needs me to log anything or some more info please let me know thanks.
Edit: thought I included this Truck has 82k miles headers and hi flow cats were installed at 5k. also idle is around 630 rpm and should be around 900.