Guys, I have an Oklahoma Joe, off set, have sealed around fire box with High Temp calk, got new thermometer, get temp up to cooking and once it starts dropping Iopen fire box to get more air flow, still dropping, I add a chunk of wood, 15 or so later I'm 30 degrees over cook temp. Food either cooks way to fast or way to slow. I haven't gotten the convection plate yet, will it help?? Looking for any advice here or suggestion????