I have an 05' fx4 supercrew. Over the past couple months Ive had a random sort of grinding noise pop up from my front section, when I slow down and stop it makes two chunking noises one on the right and then one on the left....start moving forward again and it goes away. It only does it about once a week on longer trips. I cant see anything visually wrong and there are no diagnosis codes. seems like my 4wd is attempting to engage itself, I pulled the 4wd relay and it still does it. This sound familiar to anyone? im looking for any suggestions.