Mix together the peanut butter, oil, sugar, eggs, vanilla, zucchini and peanut butter chips in a bowl. Set aside. In a separate bowl, mix together the flour, salt, baking soda, and baking powder. Add the wet ingredients to the dry ingredients and mix just until combined.
In a small bowl, combine the brown sugar, flour and softened butter. Mix until the streusel is crumbly.
Grease and flour two loaf pans. Split the batter between the two pans. Divide the streusel topping between the two loaf pans, sprinkling the streusel on top. Bake at 325 degrees for 1 hour and 5 minutes.