P0171 and p0175, Lean and Rich, Real conundrum

[SaltyC20]

Hello all. I have a 1969 C10 with a 4.8L swap out of a 2004 Tahoe with a 4L60E. I am currently experiencing two codes P0171 (Bank 1 Lean) and P0175 (Bank 2 Rich). And to top it off it recently started showing P0756 (shift solenoid), but I am ignoring that for now.

The engine runs well. At high RPMs it has plenty of power and can really spin the tires. But off the line it often stumbles and even pops on the passenger side exhaust (like its rich). By the time I am exiting the intersection, the engine picks up and I inadvertently spins the tires, as the power comes on very suddenly.

The truck is DBW, and the swap is recent. My computer is from Brendan at LT1Swap. I have replaced the spark plugs, and they all looked like a rich mixture. I have checked for vacuum leaks by spraying carb cleaner, but cannot seem to find any. The engine came with the O2 sensors cut off the harness, so I bought a pair of new boschs 15895 off ebay. I also checked for exhaust leaks upstream of the o2 sensors, but don't have any.

My brain is spinning with possible problems: Maybe burning coolant, I botched the harness job, bad head gasket, etc. Too many maybes. Please help me troubleshoot this bad boy.