Aaron, it looks like you figured out how to get email notifications of new posts. At least it looks like it in the system.

-- 140psi is TOO high! Prevost says the max pressure should be 130psi or less. This for 90% of the coaches is easy to set at the air compressor mounted compressor.
-- Your air system is probably purging frequently due to a significant leak. You may not have a Prevost aux air gauge, so you won't know how fast air is bleeding down on the Prevost aux side.
-- There's not much that will make the rear squat on both sides at the same time. I think the tag logic on your 96 should be the current logic. If not, as soon as your Prevost aux air drops your tag axle will unload and not carry any weight. TRy this. Dup your tag next time you park and them let the coach try to come back to level. It may take several minutes. Then shut it off and see if the rear squats again.