Some quick background:
While idling, my 2007 Ford Focus "revs" at about a 1-second cycle, you can hear the engine subtly go "wroom / wroom / wroom". It has issues with long crank times to start and sudden loss of power while driving.
I have recorded about a minute of the engine idling. You can see the fuel pressure cycle as the engine revs - as the fuel pressure goes up, the engine revs up, and then back down again.
What is a "normal" fuel pressure reading? Is the fuel pressure cycling like this indicative of a fuel system problem or something else?
Here's the fuel pressure:
And here's the RPMs overlaid on them. Note that they diverge towards the end - I'm not sure this is correct; while recording it I was watching the pressure chart and the sound of the engine correlated exactly with the pressure, so I'm wondering if the drift is a delay in the recording.. not sure.
In case that's not helpful, here's the complete reading of all the metrics: https://docs.google.com/spreadsheets/d/1AahZZ-ru4P5d3NkOs5fiPIgjKXZeIMLhq7RFlKQYxj8/edit?usp=sharing