than I am, but I agree it is too rich across the range. With an average of 13 PSI & 17 PSI max you should not be falling below 12:1, I would expect an average ratio of 11:1 for something pushing over 22 PSI. Your pressure is peaking at 17 about 4500 RPM and the AFR is following it, then as pressure bleeds off the AFR keeps getting richer for awhile and does not get in back in line with the pressure. I think your cylinders are getting washed by the excess fuel.