Normally a ill fitting lid will not affect temps in that manner, Your starting with to large a fire mass to keep the temps down to where you want them 8-10 briquettes will get you where you want to go. If you want to cook a 225( beyond me why I digress) start closing off your intakes at 150, and 200 close the ball valve 1/2 way and let it settle down. Then fine tune to your target with the ball valve adj. Once you learn where the sweet spot is all you will have to do is set the valve and close off the other intakes as I described. Now After trying this If the temp is still unruly I would say you have an air leak around the nipples. Easily fixed with a bead of RTV
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