OK - So I got my new Brinkman Grill and the directions say to cure it before use. The people on this forum all agree that it needs to be done. So I oil it down and start my coals as directed. I am supposed to maintain a temperature of 225 for two hours and then increase it to 400 for 1 hour. The porblem comes when I close the lid, the temperature immediately spikes to 400. How do I maintain a lower temp with the lid closed? Please help! the coals are on the grill as we speak.