Need help with 2000 galant

My wife has a 2000 Galant ES (V6). We replaced the battery and now the car will start and run but eveytime you slow down for a stop sign or traffice life that car dies. It will start right back up...

It just cuts off when you slow down. She works with some guys in a garage at the university. They hooked her car up to the computer but no codes are reading. What can I do to try to correct this problem without losing a arm and a leg at the Mitsubishi dealership??

Thanks

You must check the Mass Air Flow Sensor. The same thing happened to me when I replaced the battery. When the car was in idle speed the engine died.
Adolfo