This is some time ago now back in my propane days. Back then all we were doing were the proverbial burgers, sausages, and steaks. Wanted to try ribs. Got a lovely rack all coated in sauce, put the burners on low, and walked away thinking, with tragic incorrectness, that that constituted "low and slow".
No more than 30 minutes later I went to check on them....and there, literally, was nothing there. The meat was completely burned away and even the few blackened bones which remained were in danger of disintegrating....
On a more practical level, rookie mistakes made with the kettle: too much coal...all coals in the middle....trying to cook pretty much anything directly over the coals.