Preheat the oven to 350F (180C) degrees. Line a 9x5 inch loaf pan with parchment paper, leaving an overhang around the sides. Alternatively, line the bottom with parchment paper and lightly grease the sides.
In a large bowl, whisk together the flour, cinnamon, ginger, nutmeg, cloves, baking soda and salt.
In a separate large bowl, whisk together the oil, brown sugar, granulated sugar, eggs, vanilla, pumpkin, sour cream and orange zest until there are no lumps of sugar or pieces of egg.
Make a well in the middle of the dry ingredients and pour the wet ingredients into the well.
Gently fold the mixture together using a rubber spatula. If there are lumps, give the batter a gentle whisk by hand to remove any lumps.
Fold in the chocolate chips.
Spoon the batter into the prepared loaf pan and spread the top flat.
Bake in the preheated oven for about 60-70 minutes. Around the 40 minute mark, tent a piece of aluminum foil over the top of the pan to prevent over browning. 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.