Inspected the rear air shocks which I thought had a slow leak for years. I did a "soap" test and found no leak at shocks or air lines to the shocks. A few weeks ago I picked up a Bonneville air compressor at the pik-a-part off a Arizona car as a spare.

With no air leak I decided to replace the air pump. Went to pull it and it was corroded everywhere. I had a concern getting it out as the mounts were also corroded- thank goodness for PB Blaster.

One thing I noticed on the pump I pulled, other than dust it was super clean- but the 7/32 vacuum lines (qty 3) were all but disintegrated. When I pulled the old pump, the vacuum lines were also near disintegrated. I am not sure all what these lines do, but one feeds air into the pump via a basic filter.

Headed to AutoZone, bought some 7/32 vacuum line, replaced the old lines, installed the new pump, and tested the rear air shock system. No leaks, jumped in the trunk, pump kicked on to compensate for my weight, then stopped when shocks became level.

Lesson learned- those rear air shocks may not be leaking, may be an issue with the pump vacuum lines and or the pump system itself. The picture does not show how badly corroded all the pump parts air. All places of possible leaks- but the vacuum lines are a great place to start in trying to troubleshoot a rear air shock leak.

I'm not familiar with the A/R pumps on the cars, but considering my basic knowledge of pumps, I would say a seal or check valve failed and allowed air to leak past the pump out the intake.

I am not totally sure what the purpose of those EVAP lines are for either, but I believe it has to do with a filter system to keep the air clean, which should be where the line connects to a green nipple.
The others I think are responsible for keeping moisture out of the air system, at least that is what I faintly remember from when I looked up info on this when I found all three of those lines disintegrating on my PA.

Considering the old units lines were disintegrated, it makes sense that this is what they were for, especially seeing the rust.
I don't think those lines let any air leak out, I am pretty sure there is some kind of diaphragm in place in the system somewhere, I say this because not only were mine disintegrated, one was disconnected/dangling, and my shocks were not loosing pressure.
My pump does seem to run more than necessary though, which I believe has to do with the systems level sensor attached to the rear control arm, as I replaced my shocks thinking this would stop my pump from continuously running, but it did not, however when I lift up a tad on the rear on that right side, the pump shuts off.
I need to figure out how to adjust that, as I am almost positive I do not have any actual leaks.