The fix I generally go with is to give the Kineticist a Combat Stamina pool.
Standard talents that use burn to cast a mid-combat effect (infusions, primarily) drain an amount of stamina equal to the burn cost. This stamina recovers normally.
Talents that provide long-standing effects in exchange for burn drain your stamina for the duration of the effect or until you rest for a night, whichever comes first.
So far, it's almost completely fixed the class for my group.