Fuel problem

I'm only poking my nose in here because I see you've been waiting a while for a reply. Part of your description of the symptoms could be attributed to an elusive cause that creates a similar problem with gas engines. That is a collapsing or plugged pick-up screen inside the fuel tank. If your vehicle uses a low-pressure fuel pump in the tank, you can verify this by attaching a fuel pressure gauge, then watching what happens to pressure when the problem occurs. If this is not a viable solution, consider posting a new question so the other experts will see it and have a chance to reply. Now that I posted this reply, this question shows up as having received a reply already, so most of us won't read your request for help. That does you a disservice if you wait for me to come up with something better.