In some long fights i have problems with ooming. ive read a lot about priest and ways to help. people are saying you shouldnt need to use flash heal or prayer of healing but for example in VoA on the frost boss, when people get hit with 3 stacks/ white out, all the raid is below 1/2 hp. i can only use CoH once every 6 sec so i use it on one group and spam PoH on the other groups to get them out. When there is Aoe, i find myself using PoH all the time when CoH is on CD. Should i be doing this? or should i just spam everyone with renew or just FH everyone up while PoH is on CD?
Is the reason i am Ooming so much b/c of PoH spaming when there is AoE damg? or is the the fact that i might have kinda low mana and just need better gear?
You are probably spamming PoH more than you need to.
Lets take for example the frost boss.
Whiteout has a set timer and after he has cast it you've got ~30-45seconds to get everyone topped up before it hits.
The only other damage that the raid can take is from frost orbs.
When a whiteout comes, if the orbs aren't due for a time then just throw some renews on the range. Its not necessary to have everyone at full hp the second after the whiteout finishes if the orbs are not going to be there for a while.
Towards the end of the fight there's a time when whiteout and orbs happen one after another, that is the time to spam PoH/CoH/Divine Hymm.
Think about the boss encounter and work out if from damage is constant and steady, or spike damage like whiteout. Then you can alter your play style.
If you can also time it, Use Hymn of Hope first then shadowfiend straight after. He'll benefit from the extra 10% mana you have.
If you still spam Prayer of Healing alot then alter your spec to reduce the cost by 20%. That will probably help you.