My 2001 did this several times. Start it and sounds like it is completely misfiring.. Shut it off and restart and all normal. Over it's life, it did it 3 or 4 times. Traded that one in on a 2004 and it has done it once. Simply turn it off and restart it and it is fine. Of course it happened to the wife when I was out of town but I have her trained on shutting everything off and restarting.
Rebooting will solve almost anything electronic...
