need help,car dies,then starts right back up

need help guys.i know its my only non mopar car(2000 impala 3.8)it will just die and then it will start back up.it shows no codes.here is what ive done.replaced fuel pump and filter(50 psi with key on)replaced fuel pump regulator,plugs and wires.it has a miss also,i assume the miss is related to it dying.again it shows no codes,no check engine light.its my daughters car and she needs it to get to school.what should i check or look for?i really need to get it fixed but am kinda stumped