When I tune with a wide band it's Open Loop. O2 sesnor feedback is always trying to adjust to Stoich. You want to tune the VE table from WB reading exhaust stright off the VE table. Not adjusted form O2 sensor at all. No INT/STFT and no BBLM/LTFT just reading the exhaust with no adjustment from VE table. Either disable Closed loop enable temp and double check there is no INT or BLM readings, I just did an LS PCM that had STFT working in open loop.... Or set Min Max INT and BLM all to 128.
Fuel pressure or flow could be mechanical but I didn't see an coralation. Can you see pressure while driving?
It may be the TBI converted to MPFI bin, it's all changed from Sync to Async. Could be missing a dump overflow command before next pulse width, which would cause the constanly rising and falling fuel trims? I'm working on one know and when I get some data back I'll have a direct comparison. I also built a MPFI bin in Sync as an experiment... I've learned to hate Async in TBI...