This may sound like the obvious but it's the key to smoke flavor intensity...time and temperature.
Thanks Ron. I really don't have problems with temp, I can get it rock solid around 215, usually no adjustments necessary.
I'd just try to lower your temps to 200-225 and keep it there. Don't think smoke escaping is your culprit. Though that would lead to a draughty smoker which would cause temp fluctuations.
It's not that it's drafty, it's just lets the smoke escape easily. Since it can get out so easily it never really concentrates, so the meat is just in a light haze of smoke instead of a dense cloud. The thermometers are very steady though.
I've noticed the same thing when I smoke cheese - the larger the crack letting smoke escape, the less smokey the cheese winds up. It doesn't take that large of a crack to really reduce the smoke a lot. There is a bit of balance involved in getting enough smoke without trapping too much heat and having really oozy cheese.
Anyway, I'm going to try it with a little cold pre-smoke, then stick it on the grill and see what happens. Now I just have to pick the wood to smoke it with . . . probably madrona, maybe some apple and something else.