Engine Clicking And Tapping Noises problems of the 2014 Mazda CX-5

Last year just after a month of ownership I was stopped at traffic light. The engine began to race and then slammed so hard the brakes squealed. It felt like I had been rear ended. I put the vehicle into park, shut it off and got out to inspect my vehicle. The person behind me was not close enough to come in contact with my vehicle and there was no damage. My passengers and myself were shocked by the force. I associated this event with the vehicle being brand new and maybe something just got stuck. The SUV at this time has less than 500 miles on it. During this past winter I am starting to notice the vehicle hesitating at times and a strange clunk sound in the rear end. It hesitates often but the clunk sound is random. Again on may 4,2014 I was stopped in traffic on a busy highway and the engine began to race the vehicle then slammed with enough force to make the brakes squeal and jerk the passengers and myself forward. With this now happening a second time I am fearful to drive this vehicle. I do not feel safe.