Air ride control/ air suspension?

Hello, when I bought this car, it had 96,000 miles on it, and it was in mint condition. An old lady had owned it. I have always done my own repair work on it other than the new transmission 30,000 miles ago. I own the two repair manuals for it as well. So, the car's air suspension is not operating properly. It airs up the air bags on the car but not to ride height. The compressor runs its cycle to are up the bags and quits and the check air ride message comes on the dash. Back in 2019 I replaced the air bags, compressor and the dryer. And it worked great until about 3 months ago when it wouldn't start airing the bags up all the way. I could get by, by starting the vehicle twice to air up the bags to ride height, but it slowly got worse. Now it doesn't work at all. This is what I have done so far with no avail. I have checked the air pressure from the compressor to the connection in the trunk, and I have good pressure. I was reading the shop manuals and thought it might be the solenoids on the air bags, so I changed them. No fix. Question, is there a separate diagnostic plug in for the suspension? Do you need a special scanner? I don't really like throwing new parts at it until I find the actual problem. I have cleaned all the plugs with an electrical cleaner and a small file to get rid of some possible corrosion. I have checked all the fuses. I am stumped, need your help, thanks in advance.