Slight steering wheel "shimmy"

I am getting a little bit of back and forth movement in my steering wheel while driving. More noticeable at higher speeds and especially if i hit a little bump in the road. Just very slightly back and forth. I recently replaced my steering rack bushings thinking that would be the fix.

I am running 35's with 5100's on top setting.

Truck has 300K on it.

Aftermarket UCAs have new bushings and seem tight. i can't seem to find anything that shows signs of being worn out. Not sure if i should look at replacing inner and outer tierods? They seemed ok when I had them loose to do my rack bushings.

Any thoughts on what to check?

 

Wheel/tire balance would be high on the list. Rotate fronts to rears. Try again.

 

Try a 'road force' balance if you haven't already..

Good luck..