[Titan Ken]

If your are using weight distribution bars which are adjusted properly, with the chain links set to the proper link and you're still getting too much rear end sag, it's possible your hitch needs adjusted. Notice how it can be taken apart and set at different levels.
It is very important that the ball height be set correctly to match the trailer. Sorry I don't have the proper measurement procedure to post here, but any good RV center or hitch installer should know.