Have you found the problem yet I been having the same problem ecm-b fuse has current draw.

I read your post is this truck going dead over night before you pulled the fuse and what was the amp draw when you checked it with a computer there will be a small amp draw on the battery it could take a bit of time before the computer goes into sleep mode. Rule of thumb l would not concerned if it's around 50milliamps or less.in sleep mode.also how long does it take before the battery is dead. Is this truck driven every day and is it charging correctly. Are you leaving the amp clamp or meter on the cable long enought to see if the amps go down.