My z axis tolerance is off by .05 to .12 mm everytime it moves according to report sled position and gcode using webcontrol. Nothing as high as what you are experiencing. I’m interested in if the motor solves your issue.
If your issue is that the z axis is off it may be that you z pitch settings need to be fine tuned. Here is a link to a previous post with info taken from the meticulous z axis instructions.