th400 won't 2-3 upshift at WOT

[americanmusc1e]

I recently rebuilt my th400 and then i went through it all again after the torque converter had a bad sprag and left metal in my pan.

Stock th400 rebuild with 32-element sprag and Fairbanks shift kit. Shifts normally at part throttle though it is quite a bit softer than the fairbanks equiped 46re I rebuilt for my jeep.

I finally got the kickdown wired in and about 80% of the time if I floor it on the highway it will kick down to second and hold second until greater than 6500rpm (the remaining 20% of the time it upshifts at 4000 with the kickdown on). When I let off it shifts. The 1-2 shift happens at 3600 with the kickdown.

today I pulled the governor and replaced the worn gear, made sure nothing was sticking and re-calibrated it with slightly ligher weights and springs. I took it out on the highway and for the first couple tries it shifted 1-2 at 3600 and 2-3 at 5500 with the kickdown engaged. Then after I was feeling pretty good it went back to not upshifting out of second at WOT. What should I check next?