So the other day I was driving home from work. When outta nowhere. The car started feeling rough especially when shifting. Then it started losing power and gaining. Then Barely would accelerate. I had just come off the freeway with no problems before this. So as this was happening I made it to autozone. Hoping a quick computer test would solve. And the only things that came back were a O2 sensor and knock sensor problems. So I was about to leave because the car repair shop I go to wasn't far. So I put it in reverse and it wouldn't move. I ended up putting it in neutral then pushing it. So I made it to the shop. Took sometime to find the problem and he said it was the transmission valve body. It's an 04 Grand Prix gt. Anyone have any input ? Estimate on how much it'll cost ?