Some more info I need. What are the headers your using. How long are the primary tubes, and are they equal lenght accross all cylinders. If not it is good idea to measure each tube`s lenght. The distance the 02s are mounted from exhaust ports. It can help dialing the initial ind cyl trims. If the 02s are mounted too far from engine than stock, there is some delay for the exhaust gas to reach the sensor and it must be fixed in the bin CL settings.
The new 02s perform much better now, still the cross counts are little too low.
The engnie runs too cold to my linking at 78 degrees. The thermostat might need attention or the coolant sensor is not good. At 85-90 degrees it runs so much smoother and better. Get some cardboard in front of the radiator and increase the fan points by 5 degrees. The fuel evaporates best even at 95-105 degrees coolant, you get a higher fuel milage and the engine is more efficient with all the shit from oil turning into vapors, but is too much for built lt1. The best compromise from performance and drivability is around 90 degrees.
I see you got higher blms everywhere on the right side meaning it is adding fuel off idle too. It does seems like exhaust leak to me. Try swapping the 02s and look very carefully for black sooth and for exhaust smell in the engine bayat cold stratup. Sometimes even the tiniest hole can bring much trouble and split blms.
The wideband also shows the lean condition so it is real.
If you suspect a cylinder s cyl cut test can point which ones is giving trouble. Set the afr to 12.5 and start cutting cylinders with 5-10 second delay between them. Record how much the wideband readings change when a cylinder is cut.
Did you tried to lower the rpm and the advance for more stable idle. Stock cubes cammed lt1 idles happy at 650 at Park and 550rpm at drive. I doubt the 383 can`t keep stable idle at 750-850rpm with 20-25 degrees advance. At lower rpms the surge from bad tune is much more pronounced.
How is the idle ovespeed/underspeed spark retard/advance tables set. Having 1-3 degrees there offload the iac motor jumping all the time.
Bookmarks