Truck down no way to go! IPR or IDM?

[slopoe]

I have this in another post but some things have changed a friends truck is at my house its a 97 psd you take off it runs fine for about first mile or so the starts cutting out bad and will barely pull itself , we have changed fuel filter, CPS, both valve cover harness s still no better I believe its fuel related because today when it started missing it was white smoking pretty good. sometimes you can pull over and keep reving it up an it will clear up but less than a mile its back to missing. The cel is not on. I am completely puzzled by it i feel sorry for him this is his only way to go and he works out of the truck any help would be greatly appreciated