When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
The most common problem is with corrosion on the caliper slide pins. If you pull it all apart and check the pins it will be apparent if that is the problem. A somewhat rare problem is with failing flex hoses to the caliper, trapping pressure in the caliper. But check everything else first.
If you use advanced search on this forum you will find a lot of posts on your issue.
You also may want to do the brake search on the 99-03 7.3 diesel forum.
Also, I see you only have a couple of posts. You may have to have a few more posts before the search engine will work. I can't remember whether it kicks in right away of if you need a minimum number of posts.