Talisman of resurgance is bad, try farminng toc 5(non heroic) for abyssal rune. Replace the sp/mp5 gem in your shoulcer with 23sp and the 30 sta in leg with sp/sta, although this is extremely minor. Get the emblem of triumph relic, and don't worry about getting the emblem of frost one since it's a very minor upgrade and those emblems are better spent elsewhere.

You're probably not hitting your rotation properly. Keep up flame shock, cast lava burst every cooldown, cast chain lightning if it'll hit more than one thing, cast lightning bolt. Mash keys, don't wait until you see you're done casting. If you're boxing your cooldowns between chars are probably getting desynced thus lowering your dps.

Most of the time dps is quoted for single target dps to bosses while raid buffed, that's counting cooldowns but with fights long enough that they won't be up the whole time.