Sudden issue with cruising commanded AFR

Problem has been going on for about a week now. Thought it was my wideband sensor going out but after actually feeling/smelling the issue happening i ran some logs on it.

Vehicle is an 06 silverado with the 4.8, has a spectre intake and speed engineering long tubes.

When driving it my wideband will suddenly go to a 16.0 reading and hold there, then it will swing to a 13.0 reading and stay. After a few minutes of this it will go back to acting normally. A few more miles and the process repeats. Giving more throttle when its lean or rich to get into what should be the PE area it will finally command for 12.5 af and WB shows it is getting there. Once throttle is reduced to normal cruise it will go back into being either super lean or rich. Truck has been driving fine without issue on this tune for months. Logs show that the 16.0 and 13.0 AFR is actually being commanded for some reason. This all came out of nowhere one morning when driving to work and as long as the AFR is right truck still runs perfect. Checked for basic mechanical issues and looked over all the plugs/wires for the O2 sensors and cant find anything obviously wrong.

Attachment 85482Attachment 85483 Attachment 85484

Here is the tune and 2 logs from today one cold start and one warm. Thanks for any help

Mobile atm but check to make sure you disabled post 02 test and cat test under engine diag
update - just checked and your ecm doesn't have that option - do you have any codes? are your rear o2's missing?
i ran into this problem on a few cars because the rear o2's were removed and the ecm would do a test so if you removed them id suggest put them back in

My tuner got back with me right after posting and also believed it was the o2/cat test. Rear O2s are gone with no where to reinstall them (speed engineering long tubes and y pipe), could reinstall them if absolutely needed but wanting to avoid that money put if possible. I was searching and found a few things about renabling the rear O2sand setting them to not throw a MIL so it would fail and stop testing. I dont have to worry about emissions so showing a fail dosent matter to me as long as I can stop the wild afr swing.

i tried to do that on my car but it didn't matter if i set the dtc's to no error reported - all that does is tell the ecm to disregard anything associated with that dtc problem wise but the ecm still needs to see an input coming from the o2's otherwise it'll keep performing the test so i think youll end up having to install them back on even if not in the pipes at least plug them back in and secured them somewhere under the vehicle

Zip tie the old sensors to the frame, done deal. They do not need to be in the exhaust stream.