I have exactly the same issue in a '06 2.8 JTD, just waiting for the cable to arrive to try and find out what the issue is. I've tried some of the solutions that have been offered that were similar, like the waste gate sticking on turbo, but that was moving fine, checked all the wiring to injectors, all ok.
I was thinking it was fuel related when it happened, probably a bit of the cartridge filter stuck somewhere between filter and pump, and not too expensive to fix