Hi Paul

Start from scratch.

Do a Relative Compression test.

If you have got a four channel scope, capture,

FRPS, Injector current, Cam and Crank and post the results.

Blank the EGR off (if easy to access) for peace of mind. This needs eliminating either way.
Can you do any sneaky Smoke testing to check EGR position or has the EGR got its own position sensor.?

Has this got an intank supply pump? if so hooking up a seperate supply may not work.

A leak back check is always worth while, I have had some strange results with contaminated fuel.

I hope this gives you some inspiration.

Check the fuel supply including quality and quantity of the fuel, then get the scope out and get a direction

James