1996 Chevy S-10 4 cylinder-just stops running

My S-10 has decided to start shutting down all the sudden. Husband is a mechanic and he is also puzzled. It will run fine for a week or so and then when I am sitting at a red light, it will shutter and die, turn key completely off and she starts right back up. Check engine light does not come on. Scanner check is blank, replaced O2 sensor. Replaced original fuel pump about 6 years ago. Husband took fuel line apart, replaced filter, found small pcs. of something in fuel line. He mentioned that maybe a rubber seal inside of pump was breaking down. ? Checked for burning on fuel pump connection and it was clean. This is driving me crazy!! Can anyone help or have any ideas that I have not discussed. I have used different gas also. Sometimes at idle it runs kinda rough and other times you dont even know the truck is running.