Falcon ute bad vibrations

I BOUGHT a new BA XR6 ute in March and it has had vibration problems. The torque converter was replaced at 5000km and this fixed part of the problem, but I still have a bad vibration after the car has sat overnight. It is worse in cold weather and feels as though the tyres have a flat spot. The car shakes until you have travelled about 5-6km. Have you heard of this problem or a problem with the Dunlop tyres on this car? I know they have a high silica tread content. I have been in touch with Ford and have now waited for three weeks for them to get back to me. I hope you can shed some light on this problem.