The line pressure and governor control the shift points...not the manual valve.(what the shift linkage is connected to) At part throttle the trans wants to shift at a lower rpm but you are manually holding it in the lower gear. As soon as you move the lever to a higher gear, the trans shifts. At WOT, the line pressure is so high that the governor can't overcome it until high in the rpm band. The only way the shifter will control the shift(no matter what the throttle possition and rpm)is with a manual valve body.