Lean acceleration per O2 readings (again)

[Kudzupatch]

93 suburban, 350 TBI, well maintained. Just started to fall flat on it's face on acceleration. Unplugged the EGR since I suspected the new one had failed, it improved the performance but still no power, just doesn't try to stall out now.

Hooked up the computer and once I crack the throttle the O2 sensor readings bottom out. I mean BOTTOM out and it doesn't improve till I back off the throttle and this it come way up bounced back and forth normally. O2 counts are 30 up to 60.

I had something similar once before and finally found clogged injector. I suspect this is the cause again but what else could cause this? I want to check all the components first.