There is some other problems. For the most part it sags N the back but occasionally it will sit level. Just wandering if it could be something other than the bags?
If occasionally it will sit level then it's probably NOT the air bags. Sounds more like a faulty air compressor or distributing valve.
My wife's Lincoln did the same thing. If you look under the car you'll see ride height sensors on both sides. They are attached between the frame and the suspension. They kind of look like mini shock absorbers with wiring going to them. On her car they were bad. There's also a relief valve that allows air to escape when the suspension adjusts. It could be that too. Like JetDoc I doubt it's the bags if it works sometimes. If it is the bags it's cheaper to convert it to coil over suspension. On Ebay complete kits are around 400 bucks.
Could just be a broken air line fitting.
