Honestly, if I had the vehicle here, I would remove the transmission pan to at least inspect it and determine if there is any evidence of hard part failure (metal shavings in the pan). As crazy as it sounds, a transmission filter can partially plug and cause low line pressure and lack of fluid circulation. So, that is where I would start, but I don't like spending other people's money, so I'll let that call up to you.
I'll be here. If you need anything, let me know.
Joe
Monday, June 3rd, 2019 AT 9:09 PM