TPS is such a hard thing to get accurate results on, especially with tricks getting thrown around all the time. I would say I am usually being out threated by my guilds Bear tank (although he wears dbw sometimes and what not) but I am pretty sure I am hitting the right buttons threat wise. I usually don't worry about it so much since as long as threat isn't killing people or holding back the dps it isn't a problem. Stroking your epeen vs a DK tank or something like that is pointless. Just do your job, stay alive and make enough threat to hold the boss off raid members. I would much prefer to keep up demo shout and t clap than create 1 k extra tps to prove I can.
Post your armory. What weapon/Glyphs are you using? Glyph of Devastate? If threat is an issue, have you considered http://www.wowhead.com/item=50654 as a warrior for threat? It's only a 3 sta EH loss, but another 10% DPS over http://www.wowhead.com/item=49997 . The 284 version off LK is better, but in terms of a warrior boomstick (threatstick) the H 1.5 axe from lootship is very valuable.
Glyph of Devastate is the best threat glyph out there, are you using it?
How's your priority? The TPS priority is SS > Rev > SW > Con Blow > Dev if I recall correctly from earlier posts by the guys that have run the math.