Until you said something about it rocking back in park, it sure sounds like you have a vacuum leak. Maf low voltage? Sure it wasn't MAF low frequency? That sucking sound and that code sure sounds like some unmetered air to me, that would cause it to run like shit, and since load is primarily based off the MAF it can make the car shift funny. I'd take some brake clean and start looking for a vacuum leak and rule that out.
What about it makes you think its a transmission related issue anyway? Did I miss something?