I think it is about time we had a proper review of the situation.

When you have your PC up and running with Mach3 loaded and you can get each axis moving, then we should tackle problems one by one.

Starting from basics :-
Leadscrew pitch
Belt ratio if not direct coupling
Microstep settings
Steps per
Velocity
Acceleration
Driver current

If anyone thinks something else is needed please add to the list and I will revise this post.

BTW Andrei 5.7A is less than 2% above 5.6A and the stepper should handle this.