you likely need to do a ride height recalibration on completely level ground. if you dont have forscan, you can putting the truck into engineering and test mode first (its a part of the ride height recal process and when my suspension starts acting up (i think i have a solenoid thats going bad) i can do this quickly and it resolves the harsh ride).
to put it in E&T mode, find level ground, put the truck in neutral while it is on then hit the M (manual shifting) button so the truck enters the mode so that it can be towed. shut the truck off while it is in neutral. Next, with your foot off the brake so the engine doesnt start, hit the start button then floor the gas pedal (ie push all the way in then release fully) 3 times in a row. once you've done this you will see an "ET" symbol pop up in the bottom right corner of the dash. give it a few seconds then shut the truck off. start and drive away as usual--hopefully this will help.
If the ride is still stiff or acts strange over bumps, do the same thing as above, but while you're in ET mode, plug forscan in and run the ride height recalibration (there are threads with screenshots on exactly how to do this with forscan on this site). hope this helps!