Hi VAVU,
I'm afraid I'm not going to be of much help here but I have almost the same symptoms and have carried out the same remedial actions with the added new steering box.
Nothing has changed.
My intentions for next weekend are to recheck torques, preloads, and tighten as required in the hope that things have just been bedding in.
One thing I have noticed though, is that when towing the caravan the symptoms disappear???????
Could it be rear axle related?
That's where I'll be looking next.
Gary