My car feels unstable in a straight line at speeds of 60mph -80mph. It’s had 4 new tyres, new rear shocks, new front bottom arms and drop links and a 4 wheel alignment done and still when you drive in a straight line on the motorway and go to overtake the back end feels wallowy and on long left hand corners the traction control light flickers randomly. Does anyone know what it could possibly be and what could cure the handling problem? When you just gently turn the steering wheel at speed the back end feels like it’s all over the place before it nips. I know it can’t be anything major but I can’t for the life of me figure out what’s causing it. Please help!!!