We will neutralize the insurgents in their own land: Iran. That will calm Iraq down enough for Iraqis to their to get their nation in better (but not perfect) order.
Our efforts in Iraq were never intended to be about perfection. Iraq is a strategic base of operations from which to finish the War on Terror. Iran/Syria are next, and the various closet anti-American, ethnic/religious/Euro identity fantasy mongerers won't change that plan.
"We will neutralize the insurgents in their own land: Iran."
The worst trouble-makers--the Sunni terrorists--are coming over from countries like Jordan and Saudi Arabian, not Iran.
"That will calm Iraq down enough for Iraqis to their to get their nation in better (but not perfect) order."
There are plenty of arguments to be made in favor of war against Iran, but I really doubt doing so would stabilize Iraq.