2004 Dodge Neon A problem no one can seem to find an answer

I have a 2004 Dodge Neon (automatic transmission) with about 74,000 miles. My service engine light came on about 6 months ago, but it still ran perfect so I ignored it. About a week ago, I was driving home and i heard my gears shift strangely the next thing i knew, my gear was almost like it was stuck. I couldn't go any faster than the gear I was in. I had to pull over and shut the car off in order to fix the problem. It did this to me 3 more times that night. I took it straight to a transmission specialist. They said my transmission was running good, only there was a computer code(P0562) that indicated the engine was emitting a low voltage that was causing the transmission to run funny. So i took it to an auto mechanic, who got the same code. He replaced my battery, checked the alternator and all the connections, but couldn't find the problem. This caused the light to go off, but after about 30 mins of driving it came back on and immediantly repeated the previous problem. i'm clueless. Somebody please help me. I've already spent two hundred dollars and i'm still getting stuck in traffic, pressing the accelerator and unable to accelerate.