If you're doing HoL and CoS, you defintiely should be able to clear Gun'Drak soon. Keep at it and check out the heroic videos if you haven't already, the Collosus fight with the elemental is probably the hardest but once you get it down you'll wonder why it was even hard in the first place. Hachoos video on spreading out in a circle and tanking him in the middle works wonders.