OK, the radio was really pissing me off so I ripped the dash apart tonight to check things out. I verified that the stock VX antenna is indeed powered (12v). The problem was that the Crutchfield wiring harness did not acknowledge the antenna pin and therefore didn't connect it to the antenna power. The stock antenna must be tuned to receive FM bands, as the FM stations sounded fine without power. The 12v must be to amplify the AM. So all of you with aftermarket head units that get crappy AM signals, check for the antenna power!!

Oh and as for listening to the tuner, I have Sirius and my iPod hooked up for music, the AM is for sports radio (since Sirius doesn't carry MLB). I don't ever listen to FM.