Cb2417

Hi everyone. My issue is with my wideband gauge continually going lean. It is an innovate mtx-l and I just put it in 3 months ago. I have done the re calibration and it doesn't seem to help. I have had the same tune in for a while. It is a olsd tune and was pretty dialed in aside from some minor drivability issues. WOT was dialed in to 12.8 and my cruise was around 14.7. Thought I had it to the point where I could just drive it and enjoy it... well the car had other plans lol! It started going progressively leaner as time went on. I thought this was due to temp change but it was getting cooler out so I figured if anything the AFR would go richer. I took it out today and forced 13.0 AFR at all times with my hptuners scanner. The most I could get was 14.0 on the wideband. I have ruled out exhaust leaks as I checked my headers and exhaust clamps and all seem tight and I don't hear anything resembling a leak...
as I was driving around forcing 13.0 AFR it would suddenly spike to 22.4 for a bit then back down to14.0, all the while I was steady on the throttle cruising. I have yet to check fuel pressure and change my filter but the car seems to sound the exact same and run ok except now the different wideband reading. Doesn't seem to make a difference when I increase the wot cells of my VE table either.
Any input would be greatly appreciated thank you!