We just did a 99 550 stupid duty 7.3 and found the bottom 0 rings distorted (thought they were damaged being pulled out) on four and one missing completely. We inspected the port and no 0 ring. We looked at the remainder and the were dry and we could easily pulverize them. I spoke with a Ford tech and he's seen it from time to time but never put any thought into it. This truck ran like a bag of poop when the outside temp dropped below 40, had to fire it off of either, and after it ran for a while smoothed out. The colder it got the longer it took to smooth out. This is the first time we've run across one that's acted this way and i crossed my fingers when the injectors were installed. It was diagnosed by a process of elimination. Everything tested good and the pressure sensor was clean. When we fired it up after the injectors were replaced the smoke was so bad it filled up both shop areas and an adjacent tenants space with thick white smoke. It left a puddle of goop on the floor from tail pipe drippings. The owner has been using it like this for in his own words "ABOUT A YEAR AND A HALF"
things like this just amaze me.....