Is it the non adjustable dizzy that doesn't turn to adjust my mates bigblock was 1 tooth out on the rotor phasing and it did similar he also had the injectors out of order

And have to change bank assignments in tune so the O2s read the correct cylinders for missfire detection etc hard for the ecu to swing o2s if the banks are messed up

Check the injectors are wired correct you have to shift them to the right cylinders to match the firing order it can't be changed in the tune have to physically shift them or they run a little off...