this is what im doing (most fights, not trash etc) stealth - garrote - hfb - snd - mut - mut - env - mut (mut again if need) - env, etc etc
any advice as to what i may be doing wrong?, and what caps am i looking for, etc expt, hit, crit, haste, arm pen, looked around but all i seem to find is alot of diff numbers about what i should have. It could be probably i just have bad weps and yes i do have a bad ring and trinkets, but still under 4k seems terribly low.
hit is way to high all u need is 320 for the special and posion cap, when you open up do garrote hfb then wait till u have 4 or 5 CP to hit SnD same goes w/ env and make sure you are using deadly in the main hand and instant in the off hand, and ur expertise is low to u want that to be up around 23 - 25
It would help to know what fights you are speaking of. As mentioned, 4k in heroics is not bad at all. In my gear (http://www.wowarmory.com/character-s...=Bl%C3%A5de&gn) I pull in the neighborhood of 5k overall. So, if you are talking about heroics then don't worry about it.
Looking over your armory, your enchants look good, you are missing a head enchant though. At your gear level all your gems should pretty much be +40 AP unless you need hit or expertise (I am a few points short on both but I would not sweat it).
As far as caps go 315 is the poison hit cap and the expertise cap is 26 (these are the numbers you are shooting for). Don't worry about haste until you start pushing around 50% crit, then start stacking haste. Armor penetration is nearly useless for mut rogues because the majority of our damage is from poisons and poisons bypass armor.
You rotation looks correct. Just remember to hold back on the envenom until you have 4-5 combo points stacked up. I usually start SnD with 2 to 3 combo points. That lasts long enough for me to stack the 4-5 points needed for an envenom. Also, don't let your HfB drop off. A 1 cp rupture is enough to refresh HfB. If you are grouped with a kitty or a warrior then it is even better, they bleed the target so just hit refresh.
If you don't already have it, get some kind of plugin that displays your combo points, SnD and HfB (I use ICEHud).
I think your dps would benefit the most from replacing your weapons. Ideally you want your highest dps weapon in your main hand. You want deadly poison on your fastest weapon to build up your poison stack as fast as possible. Instant poison on your slower weapon.