At 104K miles your shocks are more than likely done. It's not an issue of length, extenders, etc. but that they simply are not recovering well. BTW, those 2" extenders aren't necessary as they extend way beyond the capability of the shocks and might even give you issues on the compressed end, where the shock stops the suspension travel and not the bump stop. Look at the Hunner nut extension on the shocks - it's right on target for "extending" shocks.
Now that your front end is raised, your bump stops aka progressive dampeners are not doing as much work right away. Before leveling, your truck was nearly sitting on them or within 1/4". Now you're probably 1/2" or more away from them. They do help control the ride a bit and the ride is probably much worse because of the worn shocks doing more work before the progressive dampeners can assist.
Your bump steer may also be due to worn steering components like the passenger side bushing. It tends to wear out, allowing movement of the rack and promoting bump steer - a vibration throughout the truck when hitting bumps. Your whole steering rack shifts position and the truck's wheels shimmy over bumps, giving you the shakes.
Minimum recommendations:
New shocks, whether OEM or Bilstein
1/2" extended bump stops from trailduty.com
New OEM steering rack bushing, or if you're ready to upgrade, a new steering rack bracket from PreferredChassisFab. That will be a more permanent solution.
In my opinion, the Trail Duty bump stops degrade the ride a bit. They do reduce the nosedive since they reduce the gap between the bump stops and the lower control arms, but they are not nearly as progressive (soft) as the OEM ones, thus they transmit more of the harshness of the road. It's a worthwhile upgrade, but there are some downfalls too.
At 104K miles, it's also time to check all of the other suspension pieces. You could have worn upper or lower control arm bushings; worn ball joints; worn tie rod ends; worn inner tie rod/steering rack ends.
But the first things I said will likely go the furthest for you.
