GOOD THROTTLE UP TO MAYBE 1/2 PETAL IF I GO WOT ENGINE BOGGS AND ONLY WILL TURN APPRX 5200 RPMS, GOOD FUEL FILTER45 PSI FUEL PRESURE, NO ENGINE MISS, NO CHECK ENGINE LIGHT, ALSO AIR FUEL IS GOOD 13.6 WHEN COLD, BUT AFTER RUNNING 4 TO 5 MIN, GOES LEAN OFF SCALE ON METER, OVER 17.0 EVEN   IN WOT, ANY THOUGHTS OR HAS THIS HAPPENED TO ANY ONE HAVE  FUEL TUNER ON THIS UNIT ALSO AND CANT MAKE IT GO RICHER ALSO

[2015 Z Force 800 53/Trail EPS]

Interesting it goes lean after the loop closes...sounds like a control problem...or sensor input but no MIL light on.

Are you checking fuel pressure under load?