Mitsubishi Repair: car idoling then cutting out when slowing down, car cuts, charging system

Question
I have a 04 Magna, v6, ES, automatic when I start it it idols fine then after 5 minutes the idol drops real low. While driving if I slow down and break the car cuts off the last 2 days the battery has been flat when i have gone to start it in the mornings, I have replacced the battery but still having the problem of the car cutting out what could be the cause of this?

Answer
Ray,
You may have a problem in the charging system of your car.  Most commonly, the alternator may be failing.  When the alternator begins to die, it will not be able to sustain a constant charge on the battery, and your battery will grow very weak.  Even a new battery can die very quickly with a bad alternator in the system.  Have your charging system inspected, and as well as your battery cabling and starter motor.
Good luck!