I think the trick to a good roux is to slowwwwwwwwwwwwww down....you cant push it to fast...when you add ingredients ...slow means slowwwwwwwwwww....to much to fast is going to give you a mass of lumpy gunk...LOL
After cooking the meat or poultry, judge the amount of fat or oil remaining in the pan drippings. This is the most crucial part of a roux gravy. Determine how much gravy you need. You will need to adjust the fat or oil amount up or down Remove fat from the pan or if you don't have enough, add butter. Stir an equal amount of flour into the hot fat and cook at least five minutes. Add liquid slowwwwwwwwwwwwwwwwly to the roux while stirring. It should immediately begin to thicken. Bring to a simmer while constantly stirring to avoid lumps. add seasonings. You can continue cooking the gravy to make it as thick as you desire. The more you cook gravies or cream soups the thicker they become.
The liquid used can be a strong broth, milk or heavy cream, depending on how rich you like it. If it needs thinning, just add a little more broth. Unless your meat was highly seasoned, you will generally need to add salt and pepper before finishing. Yum