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[ArrowHeadJim]

Thinking out load...Sometimes it just jogs the memory...

What does it take to make this thing run...

Quickly compressing of air to a high preasure (creates heat to burn the injected fuel ), Inject a fine mist of Fuel to burn which creates more preasure to provide power , repeat.

Forget about all the changes you made and go back to the basics.

Power from the batterys: Check

Spin the crank at a desent rpm: Check
( did you notice the tach while cranking. Should move. )
You need enough RPM to get the Hpop to put out enough presure.

The IPR controls the injection presure. Not enough and you won't run.

Did you confirm the high preasure oil with a gauge? You do have preasure right?

Did you check the Fuel quality. Crap in the fuel could plug stuff up. Like your filter or injectors.

Compression: This one is harder to check but maybe needed to rule it out.

Take a look in the intake and turbo for any thing that might lead you to suspect a major engine issue.

You said you use starter fluid to start it. and it runs on the starter fluid. I would say your using an external source of fuel. Which I don't recommend. But I think is implies the possiblility that you are fuel starved. So if you have compression, I would look at the high preasure oils, preasure. The Fuel preasure. The tach while cranking. Is it cold where you are? Are the glow plugs required? if not you could save some amps by disconnecting the relay. That would also help with cranking speed. Stupid stuff like oil level is correct?
You have Fuel?

If none of these help. back track your changes and remake all electrical connections verify your connectors are in good servicable condition. Check even those you didn't disturb. Check your grounding on the electronics too.

I know this is really disjointed but it has been a while since I had to think about a problem like this.