Complete swap or?

[df2x4]

if I did hit up a junkyard that has a transmission with a "known history" how much do they run?

You can check car-part.com to get some actual prices in your area, it varies quite a bit. I got a tested good 4L80E for $500 years ago, but that was prior to the world going crazy. It seems like even used parts are more expensive these days.

 

[thinger2]

You mentioned that the throttle is like doing leg presses.
I would start with that. A stuck throttle body or its cables can cause all kinds of performance and transmission issues.
Pull the cables off of the throttle body and see if the linkage arm moves freely and returns on its own.
Then see if it sticks with the cables reconnected.
If it sticks while disconnected, the problem is in the throttle body.
If it moves freely, the problem is in the cables or the pedal or the transmission
If that is the case, disconnect the other end of the cables and see if they move freely while turning the throttle linkage.
Not unusual for the throttle valve cable to bind up or the throttle cable to bind up
I would try to fix that first then move on