Ok, there's one thing that catches my eye, and that is that well-browned flour (keeping in mind this is flour, the effect may be intensified with carbalose and its low digestible starch content) absorbs less fat so you need more flour to do the same job. In short, I think you might have overcooked your roux, reduced the absorption capabilities of the carbalose/flour, hence the separation on adding the drippings (which also contain fat?).

My success with the roux so far has been with white or blond roux, haven't yet tackled a brown roux or toasted 'flour'. If I DID I'd automatically think I needed more flour/carbalose (and BTW, where toasting the roux/flour comes in, I'd toast first -- toasting 15% more minimum, with carbalose probably 30%+ -- then stir into the fat until all the fat is absorbed, etc. etc.). If more color is then needed, I'd use my standby of Kitchen Bouquet or {{secret! but it's got good color}}...and for more flavor I'd go with some of that red wine NancyLC mentioned and maybe some worcestershire sauce, etc, as flavor boosters. Hope this helps!