Have you considered that Jerry may be right on the fuel pressure, but you have other problems that are masked by low pressure.

I have no idea about these engines. Please don't take this the wrong way. I'm sure you know what you are doing. But your problem remains. You must have overlooked something.

A sticking fuel injector is the first thing that comes to mind. Perhaps your ECM is bad or the wrong one for this engine. Just trying to give you some ideas.

Good Luck.