I have seen a few posts similar to my annoyance but not exact. I have a 99 F150, auto, 5.4, 4x4. When I put the truck in reverse it will sometimes go about 10 feet then I will hear a clunk or a pop sound. It sounds like something is stuck. Other times when I put it in reverse it is like its stuck until I hit the gas a little then it will go into the gear. This problem only happens when I start the truck up and havent driven anywhere. Or if I put it in park and turn it off and then start it back up All of the other gears are as smooth as silk and reverse works fine after I have have put it into gear and driven a little. Any suggestions/comments would be greatly appreciated.