I went back and looked through the original thread where EagleMark helped Kingcat with his tune. Take a look at the Keezer6/20/13 datalog on post 54 here.

http://www.gearhead-efi.com/Fuel-Inj...uck-soon/page4

Kingcat started a wide open throttle run at about 5:12. At the top of second gear and before the shift (5:22) the O2 voltage drops to nothing. At the same time the fuel pump voltage increased 0.2 volts. It is possible he has a fuel supply issue. 355Chev experienced the same problem with his 1995 K1500 recently. Through process of elimination he traced it to a wiring problem. To rule out all the 20 year old wiring he installed a new Dorman sending unit, hotwire kit and additional grounds from the sending unit to the frame. This solved his fuel supply issue.

I agree with Eaglemark; go collect a WOT datalog and post it up. I predict we'll see the O2 voltage drop and the fuel pump voltage increase when the engine falls on its face.