insufficient data for me

when the car "dies"

and you turn the key to try and start do you hear the fuel pump? Do all of the dash lights come on?

It might simply be the ignition switch going bad but again, we do not have the entire story and are limited to what the OP reports

 

well i'll start off with the fuel pressure i checked and when i started it it was at 38 or 39 psi then as it started to idle it was around 34 or 35 psi and when i gave it some gas it went up to around 39 or 40 psi, wondering if i have a weak pump???...well my camaro was sitting for about 3 days now and i was taking it down the street to the store and it was starting to sputter and when i got back home it started sputtering again and when i was trying to park it it shut off on me -_- and it started back up but started sputtering agian...starting to think my opti is going out again...but could that just up and shut off the car while i'm driving??? i meen it wouldn't sputter when i was driving it would just shut off completely without warning.

 

and to torque_is_good...when i turn the key i can hear the fuel pump shutting on and shutting off as it should, to me it sounds a little weak after i try and turn it on after it shuts off on me but i'm not really sure and the dash lights do come on and shut off as they should...

 

can you leave the fuel pressure gauge on and drive around? some how make it so you can read it. let us know what it does than. i did this with my 3.4 and had some serious pressure drops while driving.

 

^ Yeah that. Just because you can hear the pump run, doesn't mean it's putting out sufficient pressure to flow through the injectors.

 

what brand of opti was installed? when its failing, have you checked to see if the injectors are firing using noid light?

 

He can check if something in the injector circuit is messed up, which it probly is. When do you have the no starrt? I'm sure u already sprayed starter fluid in there to make sure u have spark, you need to invest in the proper noid light set from autozone, use the GM TPI if I remember right, where are you located? I can ship mine out if youl ship it back lol