Springs or shocks Or shock & springs

I bought a 92 laredo a couple months ago, It has 292.000 on it and looks and runs strong.
The touble is I live in the country and drive gravel roads daily and run across allot of ruff road conditions, the Jeep handels pretty well, cept when it encounters wash boards the back end really hammers and the XJ wants to go side ways. Of course the higher the speed the scarier the ride is. I've ordered new leaf springs and coils
the previous owner put new shocks from Napa on about a year ago everything is stock on the Jeep .
The rear leafs have sagged to 16.25 on the drivers side, and 16 on the passengers.
Any ideas?? Thanks

This is the result of a stiff and light rear end, if you want high speed stability on rough roads you need softer springs and matching shocks, airing down a litlle will help also. My jeep does the same thing, I am too cheap to fix it so I just slow down, my rear leafs are sitll good but I just put on some new pro-comp shocks, which made it worse than stock. Trial and error might help here, when you get your new springs, go down to the parts store and get the light duty soft ride shocks. If the vehicle gets bouncy, ehhh you are out 30 bucks, upgrade. Just a thought, let me know what you do and how well it works out, I would like to smooth out the rear a little

I'd be inclined to work with tire pressures since shocks work predominantly in the low frequency range. Washboard could easily be 20Hz and higher, depending on MPH.

OME suspension system, they were made for primary and secondary unpaved roads in australia and other 'less infrastructure developed' countries...