hi, i have a renault laguna 2002 19.dci , and i am having trouble with the air intake light comes on and off ,and the car just dies at 2,000 rpm's and just make;s a shutting noise ,and if i stop the car and restart its fine for a while,and then goes again ,we, have replace everthing from the turbo to all valves and the EGR valve and had intercooler checked if you have and ideas please get back to