I did those connectors too. I removed the pins/terminals from the plugs and inspected every single one.

Fair enough ! You may not like this much either but then that tends to leave the Height Sensors / Connectors...... which are the most 'resistance-sensitive' ones of course.... (and the movement of their cables could be causing the intermittent factor ?)

[On some of my other (non-P38) vehicles with 15+year old connectors I have removed quite a few recurrent gremlins by such 'hard wiring' of critical components where viable/possible, - particularly where those were exposed to heat/temperature/weather issues..]

Longer shots are the EAS ECU/Connectors or perhaps the height switch itself (?)

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The EAS is behaving pretty good since I found the diaphragm issue. NRV's are leaking sometimes causing the truck to rise while parked. No big deal to me.
I am going to re-calibrate the height sensors and check them when the weather get warmer. Also have some minor leaks from the air lines as they enter the valve block which I plan to take care off as soon as I can find a local supplier for the O-rings.

I don't get why leaking NRVs would cause that. Surely if it's parked the solenoid valves are shut and no air will reach the springs?

I never looked into why they would cause it. That is the diagnosis I came to from reading other peoples issues.