Sorry to hear about your problems man. You already had 2 visits, one more (depending on the state you live in) attempt and the problem is not fixed, you can and should file a lemon law claim. I know I would. But try to see if they can fix the problem anyway, the Nitro is a bad motherkicker!
*EDIT*
BTW, I had to go to the dealer 4 times (only needed 3 attempts for my state) for my Caliber and a faulty exhaust issue I was having. I sent a huge letter to DCX complaining, filed with the BBB, and the NHTSA. Then ultimately, I filed a LEMON LAW CLAIM. Despite having traded the Caliber in for the Nitro, my lawyers are currently fighting for compensation on my behalf. I wasted lots of time and money going back and forth to the stinky dealership I purchased it from.