[65comet]

Any thoughts? Well, you aren't going to like this one, could be expensive if you can't do the work yourself. But, might be a break even in the long run with the way those things always die. I'd swap out for a standard suspension.
I just want to state clearly to anyone else, and everyone get the word out, don't buy a Ford with an air suspension if you are going to keep it past the warrantee. It isn't if, but when will it break. And it will be expensive. I am a strong Ford man, but each make supporter knows of something their carmaker did that just isn't right. And this is one of them.
I hope that someone else that didn't know about how bad these are had a similar situation and can answer your question if you want to stay with that suspension.
Good luck. And if there isn't an answer here, you might want to try the F-150 and the FordTrucks forums. Google them, they should pop right up. They have sections on Expeditions.