On every Expedition that I took for test drives and the 99 I ended up buying a year ago, they all rode like they had worn out front shocks. Big bumps (speed bumps, dips) the front end goes up and down like a 70's Lincoln car. I replaced the shocks with a set of KYB standard shocks and saw no improvement. A month later I went with KYB red premium gas shock and it got better but not near what I was hoping for. I tow with the Expy once in a while and the ride is alarming. A month ago I bought my third set of shocks. The fronts I tried the Rancho 9000 adjustable shocks. Rancho did not have an application listed for the rear so I went with the Explorer MX6 adjustable for the rear. WOW, what an improvement! With the shocks set at their softest setting, it rides like I think it should have in the beginning. I am using a mid point setting front and rear right now and have solved the bounce and lack of control while trailering. If you are having a similar issue, you might give this a try.

 

I too switched out all four of my stock shocks to a shock sold by a local tire dealer (Les Schwab). They were a much stiffer shock and took all the bounce and body roll out of the truck. It does ride stiffer but the handling is way better especially when towing. I think when my stock shocks on my new 2011 F150 wear out I am going with the adjustable 9000 Ranchos. Cool shocks.