As I figured, the mechanic couldn't pull any codes. The altenator was the first thing I replaced. You're right, I meant to say the voltmeter, I was reading another post that kept referring to the ammeter and that just stuck in my head. When I said it was going crazy it was erratically jumping around between the first mark (12V??) and 14V. It never dipped into the red area. The lights, etc, would dim and brighten as the needle jumped around.
Anyway, the mechanic also replaced the alternator and didn't have any better luck. I believe he said the voltage finally stabilized and is normal at 14V, but the transmission is still screwed up. Let me put it this way, if the car was a straight drive I would immediately say the clutch is worn out. I know automatics have clutches in them, but this wasn't something that happened gradually.
My father picked up the car today and said first and second are fine. Third gear is okay if you are real easy on the gas, but for the most part you can at most maintain speed on level ground. I still believe it is something electrical since this happened suddenly. We will be taking it up to a transmission shop on monday to let them check it out. It will be at home this weekend, so if there is anything I can check with a multimeter, etc. without having to drop the whole tranny, let me know.