I don't know why the afr from the engine dyno isn't included in the chart, but fuel mixture was good at low 12's.
As for the cause of the loss I've been told everything from faulty torque converter, worn dizzy gear, incorrect pinion angle, tyres slipping on the dyno, you name it, even different ramp speeds of the 2 dynos was mentioned. I think the tyres slipping at a particular drive train speed is the most likely cause that I would like to eliminate at the moment. I used et street radials which I have been told can warp and flex a lot under the stress of the rollers. I am going to go back to the same dyno with some nice hard old street tyres, and also make sure the guy connects the MAP sensor so we can also eliminate reversion.