Mystic AA's don't help that much with healing, it's mostly utility.
Wowzers wrote:
I have all my experts, 120% crit chance, 20% crit bonus, 20% potency, 40% casting speed and 15% reuse speed. 13.2k health and 11.5k power.
Thanks in advance.
Should all be plenty for heroic instances. Make sure you also have at least 1000 ability mod.
Besides that, it's more likely inefficient healing than bad gear/AA, or bad play from your groupmembers that is causing the deaths.
Make sure to keep your single ward and groupward up on the tank, and use Ritual Healing when he spikis. If anyone in your group is getting damage, just use your groupheal. Cure when needed of course. As long as the tank is holding agro that should be enough to keep everyone alive.