IPR problems
 

We have a 96 f-350 with a 7.3 on the farm, we had to replace the fuel filter housing, when I had it out I noticed that the IPR was loose so I tightened up the funky nut on it and it keeps coming loose, it does run kinda rough at an idle and after it warms up it runs ok. The truck also has 315'000 mles on it.

Does anybody have any ideas?

Thanks

That funky nut holds the soleniod on the IPR. It doesn't have to be tight, but it's got to be snug. If you do a search here you'll find threads that tell you what size normal nut you can put on there to replace the cheap tin nut that is likely warped now.

Worst case order a new one from dieselorings.com.