The O2's are at least 5 years / 35,000 miles old.

They are single wire, GM or their organization Delphi brand, pretty sure, not positive on that. With one of my scanners I could see how fast they react to RPM changes. Suggestions as to changes of brand of O2's or wiring to these. Or just change them..

I will check the F.P. today. It seems that several years ago there was a wiring upgrade that was being marketed to eliminate any voltage drop to the fuel pump.
Soo, perhaps a volt meter reading at the pump might be in order as well.

Thank you for your help, Ted