First time I ran this dungeon I ran out of mp. Tank wouldn't avoid aoe, combined with poor mana management on my part. Use esuna first if the tank is above half health to prevent the poison from ticking then use cure 1. Remove poison on party members but don't throw cures at them unless they get directly but by aoe. If poison is removed right away they will lose very little health and allow you to focus on the tank again.

Also update your gear and jewelry. Level appropriate gear is a must. Even the basic gear from the store will be better than the unique items that are 10 levels too low.