Control Pressure, measured in the line between FD and WUR, at 20 deg.C,
should be 1.0-1.5 Bar. At 40C. (WUR temp) less than 2.5 Bar.
If you are observing up to 4 Bar control pressure, that is almost certainly the source of inlet popping and shut-off, due to extreme lean mixture. If the WUR were not receiving power, the temp. and the control pressure would be lower (until engine block temperature increased).
What are the last three digits of the Bosch number on the WUR?

System Pressure, measured at the supply inlet of the FD, of 5-5.6 Bar is normal.