Amber, Have battery and alternator checked to be sure they are functioning properly. Make sure all grounds under the hood, in the cabin , battery connections and the ground buss are clean/corrosion free and tight.

Ground Buss corrosion is sort of a known issue that can make the symptoms your vehicle is demonstrating.

The ground bus connection is at the bottom of the a pillar where wires run under carpet or front door kick panel/ rocker/sill area, I believe there is a ground buss on both driver and passenger sides of the car to check and clean/repair.

Will post links to show ground buss. Check the attached links,instruction and guides. Good luck

I hope this helped you out, if so let me know by pressing the helpful button.

http://www.pontiacbonnevilleclub.com/for...

https://www.google.ca/search?q=pontiac+b...