When setting the cruise control at 25mph up to 55 the vehicle picks-up speed. Depending on the length of the hill the vehicle will pick-up speed from 10 to 20 plus mph. I tested the cruise going down a long 4% slope setting it at 55mph. The vehicle picked-up 10mph then applied the brakes dropping back 5mph. I have taken the vehicle to the dealership and all systems checked out. I also contacted Infiniti and explained my problem and they suggested I test drive one off the showroom floor. I did and the new one had the same problem. Is anyone experiencing this problem?