I think it's odd that up to 3600 fuel flow was increasing with RPM and torque as it should. Then starting at 3700 it dropped to a low at 4100 and then recovered such that at 4300 you had the same fuel flow as 3600. It then began increasing again. So, how can you have an increase in RPM, with lower fuel flow and torque? The only explanation I can come up with is that the dyno didn't load the motor up in that RPM range. Did you do more pulls? If so, how do they compare?