Here's your tip
Governor pressure commands the auto shifts, working against line pressure.
Throttle-Pressure joins with line-pressure to fight against governor pressure .
Therefore, if the trans stays in gear at WOT, long past a "normal" upshift rpm. AND
Downshifts early, you can bet that the governor pressure is too high.
That rarely happens, unless
You changed the governor parts, changed the rear gear ratio, or put the governor springs in the wrong places.
But since it's also back-shifting 3-2 very early, you may also have a pressure problem in the Direct clutch.
I recommend to
get a service manual, and a couple of pressure gauges, and follow the diagnostics.