Preheat oven to 350 degrees. Sift the flour, baking powder, and salt together in a medium bowl. In a large bowl, whisk together sour cream, 1 cup of sugar, eggs, lemon extract, and vanilla. Add the dry ingredients into the wet, whisking to combine. Use a rubber spatula to fold in the vegetable oil. Pour into the greased loaf pan and bake for about 50 minutes. While the cake is baking, combine 1/3 cup sugar in a small saucepan and 1/3 cup lemon juice over medium heat until the sugar dissolves. When the cake is done allow it to cool before removing it. Poke holes in the cake and pour the sugar-lemon mixture over it and allow it to soak. In a small bowl combine the powdered sugar and lemon juice, whisking to form a smooth glaze. Pour over the cake and slice and serve.