hi golfpropsychguy,
I'm sorry to hear about your step 2 failure. I think the answer to your question is based on how well you do in UW. I would use your UW percentage to predict whether or not you would pass for the second time. You can take the NBME tests too. As long as your scores are persistent above the passing score (I think it's 55%), you should be ok.
Good luck!
mrdowntoearth