Hey folks. Needs some advice. 2012 terrain front wheel drive. Developed a vibration and the best way to describe it a noise almost like the sound of a helicopter while at speeds of about 40mph and above. Only does it randomly. Sway bar end links have been replaced and new tires have been intalled but the same issue still ocurrs, but again, only randomly. Ball joints and tie rods seem good and tight. Truck has about 130k miles. Any suggestions?