Custom 3D printer Help

So i have build a 3d printer and I'm having trouble with my Z Axes stepper motors moving unevenly. so my print bed stays stationary with my z axes moving my X & Y Axes up as it prints. since i have a lot of weight to move up with the X & Y Stepper motors and two Hemera Extruders on a square frame, I have 4 Z Stepper motors with lead screws to try and mov it up evenly, they are wired together 2 in front and 2 in back and hooked up to a ramps 1.4, i have got a few good prints and i use a BL Touch to help Level my bed but after a few prints i notice that the Z Steppers didn't move in unison and i have to adjust them. i feel like their not getting the same power or something. when i wired them up i used the same amount of wire for each setup. is there something i can get to insure there getting to same voltage all the time and just use the ramps board to apply the movements? thanks for any help!
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