99 f350 & lately if I dont plug it in even if it's like 40 out for like the first 30 sec sounds like its only running on 4 cylinders than it'll just even out & alls good. thinking glow plugs here. i did replace them last fall unfortunately with the cheep ones that I been now reading bad things about.

 

Is the lump of iron under your hood a 7.3L Power Stroke engine?

 

yep7.3. & like I said only cold. starts fine if it's been plugged in or already warmed up