Hey guys. I have a Weber Silver B that seems to cook too hot. When preheating the grill it shoots up quickly to well over what the thermometer will read and almost back around to where it starts at 140. I've tried 2 different weber thermometers with the same readings. I contacted Weber and they said it had to be a manifold problem. I got the new manifold/regulator today with no change. With all 3 burners on low and nothing in it the grill reads around 500. The burner tubes are all in good shape. Flame looks good. Not really sure where to go from here. What temps are normal for this grill? Appreciate any help.