Engine Exhaust System problems of the 2012 Lincoln Mkz Hybrid

September 25, 2014 - while driving approximately 40 miles per hour, the "stop car safety now" warning came. I have about 91,000 miles on the vehicle. I had the vehicle towed to maplecrest Ford Lincoln. They have checked the vehicle, driven it, check for codes and have found nothing in three days of checking. They told me that they contacted Lincoln's tech team for assistance. The tech team cannot determine what is wrong with the car. The two options that I have been given are 1. Do nothing and see if the problem recurs or 2. Change the exhaust purge value reflesh & power control module. But they have no idea if this is correct any problem. Lincoln is not guaranteeing that changing this module will fix the problem since they don't know what the problem is. This is the second time that I have received the "stop car safely now" warning. The first time was in August of 2013. I filed a complaint then, which was as follows: August 19, 2013 while driving approximately 25 mph, the stop car safely now warning message illuminated as the vehicle independently decelerated. The contact shut the engine off and was able to drive without failure after restarting the vehicle. The manufacturer was made aware of the failure. The vehicle was not repaired. The approximate failure mileage was 51,000. However, I did have the car "repaired". Liccardi Ford replaced the throttle body air intake . . On or about August 20, 2013.