My 1992 GMC with a swapped 5.3 from a 2002 Silverado is going really lean on WOT. I can see it go to 16.00 on my wideband and to 1.08 lambda on the scanner. The injector duty is also going way high. The truck has a 99 Silverado stock fuel pump.
Please look at the log between frames 4950 - 5089. That section is pulling on the highway, WOT in 2nd and 3rd. The truck is a standard shift. If I need a different pump so be it, but I thought the stock 99 pump would handle this motor.
The motor is all stock other than a CAI.