New front tire is less than 1000 miles old. Rear is new as of last year. I did pull the front today and checked. Correcting the balance improved the situation, but didn't cure it.
My theory is that when I installed the taller zrx kybs, thereby reducing trail, I sacrificed some high end stability.
I think if I can reinstall stock length shocks, this will confirm or deny my theory, and I can react as necessary. Ie. look elsewhere for a solution if I'm wrong, or install a damper if I'm correct.