Wiring issue

I am nearing the end of my MPCNC build. However there’s some issue with the wiring which makes my axis vibrate upon moving them by hand (powers cut from MPCNC). These are the motors I have on MPCNC. I must be doing something wrong when I try to wire them up based on MPCNC wiring instructions (parallel connections).

I’ve connected my black (A) wires together and same goes with green ©. Black and green wires makes a coil.
For the red wire (B) I’ve connected it to red wire of the first stepper motor and to the blue wire (D) of the second stepper motor. Now the blue wire (D) is connected to the blue wire of the first stepper motor and to the red wire of the second.

To make sure RAMPS in itself won’t make the problem I’ve detached stepper motor wiring from it. Issue is that when I move axis (either X or Y) very slowly it moves without problem. With a little more speed it starts to vibrate as there is some drag on this axis. If I detach wire from the second stepper motor the problem disappears. So does if I detach only the first stepper motor. The very same happens if I detach wire from a stepper motor coil to each other (for example black (A) to green © and closing the connection). By doing this the magnets from the coil activates and starts to resist movement.

Have anyone got any idea how to solve this out? What I’m doing wrong? Is it possible that the motors are faulty?