Truck won't accelerate smoothly, revs high and shifts hard
 

I have a 2000 Dodge Ram 1500 5.9 v8 and since my dad gave it to me it would occasionally get stuck after being at a complete stop, then rev up and jolt forward once it finally shifted, but this happened so infrequently that I didn't care or think that it was an issue. Last year my transmission suddenly blew up (cracked housing) so I replaced it with a good transmission (or one I thought to be good) from a junkyard. I rebuilt the transfer case while I was at it because it had been a long time since I could get it to go into 4-wheel drive. I got it all back together and it drove and shifted like butter, but still had the occasional jolt forward when shifting. A few weeks ago it started doing this more frequently where it would rev up to about 3000rpm and then jolt forward before shifting when coming out of a complete stop but still did not happen every time. A few days ago I was on the highway and the truck would rev up but not accelerate. The next morning it did the same thing, every time I tried to accelerate it revved up to 3000 or more rpm before shifting, and this problem worsened when I tried to go up even a slight hill. I did some research and made sure the tranny fluid was good and at the correct level.

My guess is the torque converter or clutch packs have gone bad, but I would like to know what more experienced people think the problem may be. Any insight is appreciated.

I've added some photos below of when my friends and I replaced the transmission for your enjoyment.
https://cimg8.ibsrv.net/gimg/dodgefo...71f1972eb.jpeg
https://cimg7.ibsrv.net/gimg/dodgefo...e8ad2c15a.jpeg
https://cimg1.ibsrv.net/gimg/dodgefo...2c8dc271b.jpeg

I just realized it's a 2002, not a 2000, whoops, is there any way I can move the post to a different section?

Unplug the 8 pin connector on the drivers side of the trans, about halfway back. That will disable the electronics, and thus, there will be NO automatic function at all. You will have to shift manually. Go for a drive.... if the truck goes into the gear you tell it to, when you tell it to, you have an electronics problem, and replacing the governor pressure sensor and solenoid will likely fix it. If it still exhibits undesireable behavior, it's likely rebuild time.

What kind of rims are they?
https://cimg6.ibsrv.net/gimg/dodgefo...2b18864549.jpg
If you are experiencing the the same problem with the "new" trans the problem is elsewhere. No codes? Possible check valve stuck.

I pulled the plug in the area that you described (it was a six-pin connector) and I don't think that was the correct one because the truck wouldn't even turn over with it pulled.

Nope. It's an 8 pin. Plugs straight down into the top of the valve body, on the outside of the trans case. If you have a 4x4, yeah, its fun to get to. Drivers side, about halfway back on the wide part of the trans where the valve body is. There is a bit of a 'shelf', and its on that.

I have no clue what rims they are, they came with the truck, and there is nothing on them to indicate what they may be. And you are right about there being no codes.

I found the 8-pin connector but the car still seems to be shifting automatically even with that unplugged.
https://cimg7.ibsrv.net/gimg/dodgefo...2b320436d.jpeg

https://cimg7.ibsrv.net/gimg/dodgefo...0f4396a259.jpg

See the hole second from the left? The one with the shoulder around it? That's where the 8 pin connector goes.

I pulled the plug but it still seems to be shifting automatically, is there a certain way that I should be trying to shift it? I would assume between 1,2, drive, and reverse