1999 Ford Expedition - Intake manifold gaskets

Hi Folks, I have a 1999 Ford Expedition. A couple of days ago The engine started losing coolant as soon as the engine cooled. I replaced the coolant only to lose it again when the engine cooled. I was told that it is more likely the intake manifold gaskets leaking. It seems they are right. What is the cost to repair if I take it to a mechanic? any idea? Thanks for your help.

if it has the 5.4 alot. they are a pain in the ass to work on.