Just a thought...
As an alternative to all these attempts to rip the Pandora mp3s direct, perhaps you might like to consider the solution that I turned to after very limited success with the methods discussed at such great length above.
I use a program called Replay Music http://www.applian.com/replay-music/index....aming-media.com . You have to buy it (shock; horror), or you can download a free trial, but it's very useful. It records tracks you listen to on Pandora (or any other internet source), and then tags them using Gracenote. It works pretty well; a bloody sight more reliably than any other method I've tried.