Well, if the smoker has air leaks, you will not be able to control the heat, for even heat distribution.... and the smoker will leak....
Time to sit back and think.... if the door is tight on top, cut the hinges loose... look for where the door doesn't fit... maybe the hinge on the door is holding up the rest of the door... I've seen that happen.... when the hinges are welded, the weld "PULLS" the door and then the bottom doesn't fit...
Take a picture, from the end of the smoker, showing the entire door and how it fits following the curve.... we can probably figure out where it needs to be tweaked and the easiest, best way to tweak it....
did you fix the air intakes..... so you could close them.....
Dave