I have had this issue a few different times, but recently it happened three times in a row while driving. While on a freeway or fast road, the vehicle speed will suddenly slow down to 20mph. You must pull over to the shoulder and restart your vehicle in Park position. It would be very dangerous if you were driving on a grade or any highway, especially one without a shoulder. My check engine light came on and flashed. I took the car into the dealer and they diagnosed it as a Rocker Arm issue. They are replacing the engine at this time. I do not know if the rocker arm broke off or in what way it was defective. My tow truck driver said he had just towed another new CX-5 to the same dealer the day before. That Mazda had the very same issue of sudden loss of power. Personally, I would consider this a “recall issue” due to the safety concerns.