2000 trans am 4l60e high stall flares during shift

My transmission was rebuilt a few years ago. It has upgraded clutches, band, boost valve and Hughes 2500 high stall. At WOT it seems to flare during shifts and hits the rev limiter. I've lowered RPMs for each shift but still can't seem to get it right. Also during downshifts it seems to flare when shifting. Like if you are doing 55 at 2000rpm cruising and go WOT it will hit rev-limiter before downshifting. Part-throttle shifts and everything else seems fine.

Any help would be appreciated.

needs a rebuild,, you really need to put some $$ into hard parts to make a 4l60e hold power and a trans shop that specializes in these transmissions,,