at high load, your o2 seems to be reading too much fuel, so your ecm is responding by removing quite a bit of fuel. this might be a symptom rather than a cause. just for fun, how does it run with the o2 unplugged (and reset the ecm by disconnecting the battery for a bit)?

is there anything you might have changed/swapped that would increase fuel or restrict airflow, adjustable FPR, different injectors, anything like that?

i would tend to look for a mechanical problem too, you have a lot of unburned fuel, not making a ton of vacuum.

how intermittent is this thing anyway? can we see a log of it behaving normally under heavy throttle?