Shakeywarrior

So i got my transmission rebuilt, replaced the cat. When the car heats up it starts making this whining sound then begins to slip gears and eventually doesn't shift into any gears and just revs. But if I shut it off and let it chill for a few minutes then turn it back on it shifts into gears but ends up doing the same things i explained. It's a 04, AT transmission (yes I know it's not manual but I don't care I love the car), has a little over 130,000 miles. I've replaced the spark plug wires, spark plugs, and ignition coils not even 5000 miles ago, I make sure the oil is always filled and never low, it needs a oil change actually but I need my tires rotated so I was just gonna take it in for the little deal at my local firestone but I can't even drive the damn thing. I also put premium gas only. Anyone have the same problem or know what's going on? Is the the car finished? Also the last owner told me she had the engine replaced and put not even 30,000 miles on it which is why I bought the car in the first place for only $1000 flat.

Update: took it back to transmission shop they're taking care of it.

Update 4/18: once again it's doing it. I took it to ammco and this is the 5th time it's going back. It's under warranty so I'm not paying for any of the work but what the hell is going on. I got it back yesterday it worked fine. Then today I was driving around after getting the oil changed, car washed, and getting gas while also doing some errands it started to make that grinding noise then starting slipping. I pulled over and checked the fluids and the transmission fluid wasn't dirty and it has plenty in it. It's like it's overheating or something. What the hell is going on!?!