91 Prism-changed fuel filter, didn't work

I changed the fuel filter in my 91 prism. Seemed to do a little better but after I drove it more, it still dogs out when you shift down, or stop. It just wants to die out. Also, once it has ran for awhile and you shut it off, it doesn't want to start back up. I need to put a new muffler on it, as the one on it now is totally rusted through and not connected at all. May sound stupid, but would that make any difference? Any advice at all would be appreciated. Thanks.:banghead:

Try the coil pack on the distributor.

My bet would be the Idle Airflow Sensor.