Well it can't be EGR. I have a bypass fitted but also kept the solenoid connected electricaly to avoid any codes.

Couldn't believe it, but today the car has now destroyed a vibration damper (main pulley). Managed to get it home with the A/C turned off. Wondering if this is what was causing what felt like misfires.

Once I get this new problem fixed, I will get INPA working whilst driving to watch rail pressure and low fuel pressures.