Car doesn’t move until high RPMS.

True.
My 96 1500 4x4 did that.
Change the main valve , updated versions send flow to the convertor in park.
I still put it in neutral right after I fire it up anyways out of habit 'the rebuild and out and in labor cost me 2,700' ouch.

I’m hoping that is all it is but I’ve never had that issue in the past. I’ll check the fluid with the car running tomorrow and since it will be in neutral at that time it should help with the drain back issue to. If neither of those things help then we got bigger issues.