Put the giblets and neck in a small saucepan of water over medium heat and bring to a boil. Turn the heat to medium low and simmer until the giblets are cooked, 45 minutes to 1 hour. Remove the giblets and neck, set aside and keep the water in the saucepan.
In the turkey roasting pan (which should not have been cleaned!), add back 1/4 cup turkey fat. Sprinkle in the flour and whisk it into the fat to form a paste. If the paste is too thick or clumpy, add a little more fat. If it's too greasy, sprinkle in more flour. Whisk and cook the roux over medium-low heat until deep golden brown.
Turn off the heat and add the whiskey, then turn the heat back on and whisk it in. Pour in the chicken broth, whisking the whole time, then add the maple syrup. Allow it to cook and thicken for several minutes, whisking occasionally. If the gravy gets too thick or if it's too salty, thin it with a little of the giblet water. If the gravy is too thin, just keep cooking until it thickens up. Taste, then add salt and plenty of black pepper. Chop the giblets and add them to the gravy. Remove as much of the neck meat as you can and add it to the gravy too. Serve immediately!