Intermittent miss (lope really)

[mhuppertz]

Need some guesses on what this could be. It started before I replaced the head and I thought the new head would fix it, but it was not to be.
Sometimes it idles perfectly smooth, and sometimes it idles (and off idle also) with something less than a miss.

I don't know what would come and go like that, but has to be the pump or an injector.

Thoughts?

[93flatbed]

Supply air leak. Cam plate return spring broken(which my 12mm pump just did...again has kinda what you are describing but only after a very hard run). Loose connection at the FSS, or bad voltage supply to FSS. These are only my thoughts, I'm sure there are some smart people on here.......somewhere?

[RCCUMMINS89]

My thoughts go to sucking air somewhere.

A broken return spring or the likes usually cause it to "hunt"

[Greenleaf]

I had a set of injectors do that. They had high mileage. It did just as you described. I changed them out and it really smoothed the idle.