The rue you make is not cooked enough.. take butter and flour cook together in pan until hot and well mixed take small amounts of rue and add to your gravy which should be hot, not boiling hot, beat with whip continue to add rue until gravy has reached desired thickness.
Pour off some of the excess fat in the roasting pan juices. Take about 1/2 cup of milk and add 1-2 TB of flour to the milk in a jar with a lid. Shake it well. After you bring the brown drippings and a little fat to a simmer, slowly add the flower-milk mix and stir well with a wisk or similar tool. Bring the gravy to a low boil and then reduce the heat. Add seasonings, not vegetable juices, and let simmer for all the flavors to blend. You can add more milk or water to increase amount of gravy. Ok to add a little more flour if it's too thin.
I like to add salt, pepper, onion powder and poultry seasoning. Taste occasionally to be sure you have enough flavor. I never have lumps when I make it this way. The milk makes the gravy creamy and blending it well with flour before you pour it in prevents lumps. It works great every single time. Good luck!
Other people asked questions on various topics, and are still waiting for answer. Would be great if you can take a sec and answer them