If you have trouble with trailer sway, first make sure that you have enough tongue weight. It should be around 10% of total weight (trailer and load), although I have towed 9,000 lbs. of boat with only 550 pounds of tongue weight (around town and short 20-mile highway jaunts) the past few years without sway issues. Did this with my 2003 Exp. FX4 and the new 2016 King Ranch 4x4. If the trailer sways while you are driving, you should reach up on the dash and activate the trailer brake carefully (i.e. slow down using the trailer's brakes). Hitting the brakes on the tow vehicle might worsen the sway, especially if your trailer brake setting is too low. Set your trailer brakes so that it surprises you a little how quickly you are decelerating. The trailer should feel a little like it is stopping the tow vehicle, not the other way around. First time I towed with the King Ranch the trailer brake was set on 10. I hit the brakes and the trailer brakes locked up and skidded until I came to a stop, even after I let off the brake! I find that 4 or 4.5 is about right with my horse trailer and with the boat.