Why does the merc lose air in the air suspension making the rear end go done about 3 inches and everything checks out ok?

Recheck all air line,s there is a leak somewhere in the system.

Slow leaks are hard to find,soapy water sometime,s help,s you find the slow leak,s.

I had the air bags replaced on my '04 Grand Marquis. Now it leaks down overnight when it didn't before. The shop which replaced the bags checked the connections to the bags, etc. and couldn't find anything wrong. I took it to another shop and they couldn't find anything either. It didn't do this before replacing the bags. They had cracks in them and wouldn't have lasted long, so I'm glad I had them replaced. But since the car didn't settle overnight before, I know this isn't right. Any ideas?