03 silverado 5.3 need help

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hey guys i purchased a truck and it feels way down on power ive never tuned anything before and want to learn but im completely lost any help would be greatly appreciated
5.3 gen 4 rods flat top pistons btr stage 3 cam 3200 circle d converter
truck runs and drives but is insanely rich at idle and has no power just about falls on its face and i dont know where to start
i have a AFR gauge on the way so ill be able to give more info if needed
file that came on my truck.hpt