the trick to not running out of mp in the ifrit fight on THM is to start spamming combos later (like start in phase 2, and have LNC get him through phase 1 for the most part) then to use a macro such as this (with action queuing on) for your combos:
/ac "Thunder <t>
/wait 2
/ac "Parsimony" <me>
/wait 2
/ac "Thundara <t>
The cooldown on parsimony is long enough that if you use the combo whenever Thundara is ready, parsimony will be triggered every other time you use the combo. Remeber to fight with you weapon put away, and sit down at the tanks feet when Ifrit jumps.