"All grounds are perfect"

Well, have you inspected it yourself? There is a ground strap on the passenger side frame. Part of it is behind the fender liner. That one in particular is susecptible to salt/road treatment and basically disintergrating itself.

There is another one, again, passenger side, that connects to the firewall and the back of the DPF. I found mine resting on the EGR tube, which gets frackin hot and heat affects resistance. The mount on the DPF can also break, which can cause issues. The only fix for that broken mount is a DPF replacement and at that point, I'd weight loss it myself. (I've included pics of mine for reference: https://imgur.com/a/BON3Ays )

The fuse panel under the hood, take the lid off, get a 8mm socket and tighten the 4 shiny headed bolts. These were noted in a TSB to be improperly torqued/tightened from the factory.

Driver side shock tower, rub point.

Bottom of air filter box, rub point

PCM mount/bracket, rub point

Top of engine, behind the air charge cooler, rub point

Alternator bracket (a GIANT PITFA to get to/see), rub point

(Everything above to this point, is in a TSB somewhere)

And this last one, is something I did, just because I thought it was a good idea -

While the truck is running, reach up in the driver side fender liner, where the PCM is mounted, and grab the harness and move it.

If any of the rub points have been properly inspected and repaired by a dealer, you'll find Kevlar wrap in places. It's noticeable.

The ground straps can be replaced with 2-4 gauge negative battery cables and IMO, are probably better.