I've attached picture diagnostic flow charts below for the two codes P0171 and P0300 you mentioned on your Pontiac. Hope this helps and thanks for using 2CarPros.
Images (Click to enlarge)
Sep 7, 2021 at 11:51 PM
Repair Safety Notice: This information is for general instructional purposes only. Vehicle repair can be dangerous. Verify all information, follow manufacturer service procedures, use proper tools and safety equipment, and consult a qualified repair shop when needed.