My 1998 E-350 had the same problem of constant input an inch either way, and the front tires felt like they were not on the ground, the steering was so lite, now it feels normal. Your unit is much newer so it will not have the problems mine did.
Replaced tie rod ends and drag link. Replaced caster/camber sleeves for +5 degrees of caster, new Bilstein HD shocks, then adjusted air in front tires after weighing. Check the information on loading and air for your brand of tire. Mine was Firestone Trnasforce a max inflation of 80 pounds. I am running 70 pounds in the front and 75 in the rear 4 tires.
After all that, the steering was solid, but still with a little play. I had had Tire Man brass valves installed the week before and did not check the air after they were done, then installed a Safe-T-plus steering stabilizer this last weekend. When trying to adjust it we found it would pull a little to the right or left with each adjustment. We finally tightened it down on the best spot.
The next day, I decided I should check the air in the front tires. One was at 75 pounds the other at 72 pounds, left that way after the valve install. I put both at 70 pounds,(I have a good gauge.) and drove it. Did not pull to right or left, and had very little steering input mostly because of the road conditions.
I feel the Safe-T-plus did make the final difference lessening the amount of steering input, I am satisfied and happy that I made the investment.
