Preheat the oven to 350F degrees.
Grease and flour a 9-inch (23 cm) loaf pan, or line with parchment paper.
In a medium bowl whisk together the flour, cinnamon, nutmeg, ginger, allspice, baking soda and salt.
In a large bowl whisk together the oil, brown sugar, white sugar, vanilla, eggs, pumpkin and sour cream until no lumps remain. This can also be done with an electric mixer.
Fold the dry ingredients into the pumpkin mixture. Give it a few whisks until there are no lumps.
Fold in the chocolate chips.
Spoon the batter into the prepared loaf pan.
Bake in the preheated oven for 50-70 minutes. When it's done baking, an inserted toothpick comes out clean or with a few crumbs and if you press down gently on the bread it will feel firm or slightly springy. If you're unsure, it's better to bake the bread for a few extra minutes with this recipe.
Remove from the oven and let it cool fully in the pan on a wire rack. Once fully cooled, remove from the pan and slice.