Yeah...
Why, in detail:
Our a/t is close to a manual. So in drive, it's in 1st gear. Locked solid! As you accelerate, it changes gears. Unlock first, lock in second, etc...
That works, right? It shifts normal?
The next part is the 'Torque Convertor'. Between the engine & transmission. All the power goes through it. Imagine one fan, the engine, facing another, the trans. One blows (fluid in this case) at the other, spinning it, the trans, and thus, the wheels. They will go, or stop. Just blowing.
Then the torque convertor also has a 'lock up clutch'. So it will transfer all the power, and all the speed. So the trans, and wheels can not stop. They're locked. Hense, the lock up clutch. Also turned on at a speed, and turned off below.
But your car stalls, so it doesn't unlock! That is done electronically, to run a solenoid, and hydraulically. So that is several parts. First the pump, second the solenoid, third the clutch.
The pump works, because you have any gears.
The clutch works, or it wouln't stall.
I see the valve. Hanging open, causing the clutch to stay engaged. Sometimes, the solenoid is leaky or gouged to cause this. But that usually makes I stick always. So that leaves that the fluid has crud to make it stick.
If the fluid is not red, it has crud.