Delta/Kossel Mini - Printed Holes in X-Y *Help or Tips*

I have a delta/kossel mini I built from a kit off eBay and am having trouble with undersized M3/M4 size, PLA printed holes in the X-Y orientation.

I'm pretty confident the printer is calibrated well. I've checked and verified multiple times to ensure the bed is level, the X-Y-Z-E steps/mm are correct, delta radius is correct, and diagonal rod lengths are correct.

I'm using this M3 test block on thingivers : http://www.thingiverse.com/thing:381770

Attachment 8460

Using Cura to slice (PLA), if I print it oriented like the picture is shown, the 3 holes (printed in Z) shown seem to be accurate enough. I can push fit an M3 bolt into the 3.5mm and 3.1mm hole and thread into the 2.9mm.

Using Cura to slice (PLA), if I print it with the numbers/holes facing up (holes printed in X-Y), I can only thread an M3 bolt into the 3.5mm hole. The 3.1mm and 2.9mm won't take the M3 bolt without drilling.

I'm printing 0.2mm layers, 1.75mm filament, using a 0.4mm nozzle. In Cura, I've played with extrusion rate (+/- 5%), extrusion temp (195-210), bed temp (60 - 70), shell layers (0.8-1.2mm), and speeds (20-40mm/sec) with no real significant improvements. The x-y printed holes are still too small.

I've considered trying slic3r, or maybe even Simplify3D, but I would really like to know what's going on before I add another layer of variation.

Any help or tips on what next I might try to get better accuracy in my X-Y printed holes?