Problems with 98 3.8 intermittently dying ??????????

I'm so confused. I've got a neighbors car that will just die. For no reason whatsoever. There is no SES light, no nothing.
The car will sometimes take over 3 minutes to start, sometimes it will start right back up. It will die at various times, but mostly under braking. I done plugs and wires and that helped the car running, but the dying issue is still there. It does not stumble or stutter, it's just as if you turned off the key.
Her alarm will not arm. If you hit the lock button, it will automatically go off.
The volt guage will fluctuate sometimes dropping below 13v.

I perosnally drove the car and it drives fine. Just randomly dies like you hit the key. No security light or SES.

I need some help, she has had it to 3 dealers, 2 shops, and now me :cry:

-Shannon

The dealers couldn't find the problem?:eek:

Sounds electrical with it not being able to start always. When my car started dying on me for what seemed like no reason, it turned out the battery terminals were loose.

wow thats bad fuel pum has been checked
?
check the BCm **** the theft control system it controls the security system
on factory alrms it can turn off the fuel pump and it controls the doors and
chip in the key ........ check the starter i herd if its bad it can turn off the car ...... let me know what you find out t his is interesting