Base Mana is based purely on level and class. It's the amount of mana you'd have without talents and a debuff for -100% Int.
Hunters, for some reason, have the highest base mana, and the lowest Int on Tier 7 gear. That doesn't make stacking Int just for the mana a good idea.. there is still Aspect of the Viper.. but it's a good idea to bring some mana pots with you.
Perhaps even use a Fel Mana pot just before a pull to sneak in some extra mana. I don't think there's a new version of mana over time pots, but the old ones aren't bad if you're having problems.