Mostly a rant, but I'm open to y'alls opinions/suggestions.
This is a long outstanding problem of mine. Have a fast 90 and inconsistant AFR's between banks. Running a dual wideband setup, left and right bank in the primary O2 locations. I'm 99.999999999999999999999999999% sure this is a hardware problem. To date, here's what I've tried:
Swapped injectors from bank to bank, no change
Replaced injectors, no change
Swapped injectors again, no change
Found two exhuast leaks, fixed them, no change
Tightened intake manifold, no change
Double checked vacuum lines, no problems here
Found crack in #7 runner, JB weld, no change
Crack on #7 turned into broken chunk, replaced lower shell, made new gasket, slight improvement. From here, the left bank would run 2 points higher under 2k RPM. Above 2k RPM, both banks tracked within 0.5 AFR
Remade gasket, Right bank now running leaner than left
Tightened right side of manifold, right bank = commanded, left is off by 1 - 1.5 AFR
Tightened left side manifold, shit hits fan, both banks lean, left ~ 15.5:1, right, ~ 20:1
I'm not sure what's left to try.