I understand that, but lowering the target is just going to make it richer since the add vs time/rpm is still working. You are already at 11 afr if not richer.
Log the PID "Commanded AFR" and put it in your scan screen or the gauges. That way you can see what the computer is calling for an actual air fuel while driving.
I'd lower the final timing by 1-2 and see what happens.