2002 Other Mazda Models Car Dies

I drive a Mazda Protege 5. I have around 125,000 miles on it. Recently my car has been dying after I start it. At first it would putter and slow down, every time I stopped or slowed down. Over the summer I had the same problem and replaced my spark plugs, but the auto shop didn't have the wires. I just replaced the wires and it is still doing the same thing. I can start the car but sometimes it dies right away or dies every time I back the car out. Does anyone know what might be wrong.