Seems like your on the right track....If all the linkages and B/Joints check out ok,
Check the Front end alignment...Geometrically ,the front end will center the vehicle after turning.
I'm guessing you checked the tires,not low...
You flushed it so there probably isnt any restriction in the return line.
Check the steering shaft coupling ,make sure its not binding..
But i would bet you have a faulty Steering Gear Box
Rams are known for it.