I think most of what your seeing is flex in the y-axis drive rod. Try the pillow block and might as well replace those bushings with bearings also. I have a total of 6 bearings on that rod and it made a huge difference. The problem is in finding bearings that nicely fit on that rod. Not because the bearings are hard to find, because the rod is of poor tolerance. I had to spin mine in a drill press and sand it down enough to fit the bearings on.
Printit Industries Model 8.10 fully enclosed CoreXY, Chamber heat
3-SD3's & a Workbench all fully enclosed, RH-Slic3r Win7pro, E3D V6, Volcano & Cyclops Hot End
SSR/500W AC Heated Glass Bed, Linear bearings on SS rods. Direct Drive Y-axis, BulldogXL
Thanks to all for your contributions