Living in Tennessee, I've had PLENTY of good bbq to compare my own to.
Most folks don't care for vinegar-based sauces, so pulling (shredding) and mixing in a sauce for flavor is not an option as far as I'm concerned, even though so many restaurants do it. (I admit though, that I often make some "E. North Carolina spritq", without the grainular stuff that would clog my spray bottle. I have it to spritz the roast when checking and I'll use just a little when it's all done if for some reason the roast looks a little dry. I don't care for using much apple juice to add moisture.
Other than that, try using a little hickory with the apple. I don't use much: just a couple of chunks hickory and three or four of fruitwood like peach or apple. Like oak is used for the best brisket, a little hickory's needed for the best pork shoulder. I do remove most of the hickory bark, though.
You've probably already tried a lot of what I'm mentioning, but maybe something might help. Assuming your outside bark is not too dark, mix in what Gary Wiviott refers to as "Mr. Brown", and keep a decent amount of "Mrs. White" (small pieces of soft fat that didn't finish rendering) and you don't need any sauce or added rub. Take as little time and effort as you can with the meat to reduce evaporation, keeping it covered as much as possible. Keep in mind that pulled pork will definately lose moisture and flavor faster than bbq that was "handled with care." Some of the best I've ever had was at Big Bob Gibson's in Alabama, and it what left in chunks, but just fell apart in your mouth.
Hope something helped!
Dave
