Try not eating fat for a day or two and see if your stool changes. If it becomes normal, then you know its a problem digesting fat.
If it is the case, you could try a digestive enzyme to help. I suggest Digest Gold, you can buy it on Amazon.
How are your liver enzymes from recent blood work? In particular, your Alp and Bilirubin levels? Bile is the essential ingredient (created by your liver) for digesting fats and is added into the start of your small intestines. Bile duct blockages or even a mild impedance can cause you to have greasy, floating stools.