Slight steering wheel shimmy

My truck has had a slight steering wheel shimmy since new. I realize I should have taken it back to the dealer to try to resolve, but I didn't.
At speeds from 55 to 70, I get a slight shake at the steering wheel. Rotating tires changed nothing. It's not a brake rotor warp. Applying brakes has always been smooth.
Rotated tires at every oil change and it never really changed the shimmy.
At 55K miles, I had a Bilstein 5100 series leveling kit installed and went up one size on the new tires, and an alignment. It seemed to be better, but maybe it was just the new tires that felt better.
A few months later the dealership was running a special on an alignment so I got another one. The shimmy is still there.
I'm wondering if a front TRD stabilizer bar would make a difference.
Any suggestions? Thanks

 

Hope it's ok to bump my thread here.