OK for those of you who have or had this on farm - how the HELL do you deal with mana issues?

I run warrior/4 Shammies and the ONLY variable that's absolutely causing me complete and utter hell as far as that timer is MANA. I GNAW through these pats, the bosses are jokes, I have positioning down to a science for each and every set.

The issue is MANA. Stopping and drinking is killing me. The best I've done yet is downing the 3rd boss with around 3-4 minutes to go.

I'm so close I can taste it.

Suggestions?