2009 silverado 5.3 v8 lt ex

I have a 2009 5.3 ltr chevy silverado with high mileage (over 200k) changed
the oil every 3000 miles and maintained by the dealer that I bought it brand
new from. A couple of months ago I brought it in to see if they could fix it.
They recommended a $7000.00 new engine from the factory with 100,000
mile warranty or a $2000.00 to $3000.00 repair. And said I could probably
drive it for who knows how long until it broke down then get a new engine.  
The stop engine light would come on in the morning then after stopping and
starting again it would be fine all day until 3 days ago when the oil pressure
would not go above 20. So I brought it to the dealer who said I need a new
engine now. My question is should I get the filters and oil sending unit or oil
pump checked out before I get an engine. As I have learned should have
been done when I first brought it in by reading other owners comments on
the problem in this forum.