Well if its not one thing it is another with her. I will be driving down the road in my monte and the engine will just cut off and I lose all power in the car it dosent even chime when you put the key in it nothing at all it just happens randomly. I could just start it and run it for about 45 secounds and it will do so. Power does restore in it sometimes mabye right after or 15 mins later. When it does it and power comes instantly back on I says low brake fluid service tracton system and service car soon it will also display cal err on the radio not every time just sometimes. The other day it did it too me and waited about 5 mins it started up just to lose all power again. It was acting like the batt was dead all I sal when I turned the key was the check engine light on the dash very dim and flashing like it was dead few mins later started right back up. It will also blow 2 fuzes Randomly the fuzes were labled C/LTR and PCM/BCM/CLSTR. She has a brand new aultonator a week old I just replaced the ignition switch with no problem along with the dealer puting in a new lock cylnder. Have any ideas?

 

your problem could be many things but i would start by checking for corrosion on the battery cables, i usually just take the plastic guards off mine since they always clog up with that nasty gunk.