Sorry to dig up an old thread, but did you find out the issue here? My car seems to do the same thing. It will idle fine then the rail pressure jumps to 2200psi and start making a metallic ticking sound. If I blip the throttle the rail pressure goes back to normal and the ticking goes away.
Edit:
https://datazap.me/u/jmilam94/log-1702303929?log=0&data=16-22
Here is a data log when the rail pressure is high at idle. then you can see I blip the throttle and the pressure drops back to normal and then the ticking noise goes away.