What engine type does the 2005 Mercury Monterey (Ford) van have? Is it a Nissan engine?

Looking to buy a 2005 Mercury Monterey Van. I was told it has a Nissan engine by a friend. However, I can't find anything stating that.

Also, what are they known for, as far as, issues/problems? I want to know what I getting into?

Any other information including what I'm seeking appreciated.

They were talking about the Mercury Villager which was a rebadged Nissan Quest. The Montereys have a 4.2 engine that early engines had head gasket problems. But they fixed them before 05. They were not very popular but owners seem to like them. Hope you get a good deal on it, resale value will be low. http://www.edmunds.com/mercury/monterey/2005/consumer-reviews/

No Ford has a Nissan engine. Ford did make a van that Nissan bought from Ford & re-named, after all of their attempts at making their own burned.

It's a Ford Essex V6, 4.2 liter. Built at Ford's, Windsor, Ontario, Canada engine plant.
The van is the Ford Freestar (rebadged for Mercury and a bit more upscale) . All Built at Ford's Oakville, Canada plant…
Nissan never had a thing to do with them… The earlier Mercury Villager van was a joint venture between Ford and Nissan most those built at Ford's Avon Lake, Ohio plant (Nissan Quest/Mercury Villager) Some built in China. Ford designed the platform, Nissan provided powertrains modified to fit
We did testing for Ford engineering during the development. By 2005 the transmission issues were straightened out.
They're nice vehicles… Have a prepurchase inspection done, as you would with any eleven year old vehicle.