Just with lightning bolt spam you should easily pull 4kdps on trash and 4-6kdps on boss with cooldowns and heroism. Im lazy and havent set up click macros but just use lightning bolt and have lightning bolt glyphed. I do have a moonkin providing the 13% magic damage buff but I would assume that your DK would be specced to do that if u dont have a druid.

This is one of my shamans http://eu.wowarmory.com/character-sh...en+Mill&n=Xter.
As you can see theres still a lot of room for improvement on gear. Dont settle for 3k dps in t9 gear