Your Y acceleration may simply be too high. Make sure your Y motor wires are tight at every point.
Show us the mach3 screens with velocity and acceleration.
What software are you using, are you positive you are using the correct post processor.
Is this the open sign we all use for first cuts? If so that Gcode is rock solid. Send me the file I'll try it.
I have not had to change, add or send any manual Gcode commands for anything I have made since the 90's when I wrote my own Gcode. The post processors are so good now I have not sen a case I can remember where I had to help Mach3 get through the file, the issue is always hardware or in the mach settings in my shop. Even for ATC and touch plates and all types of other stuff I used to have to pump out a few lines of Gcode just dont require it any more, UNLESS I write the Gcode file myself. The post processors are just better than me at this point by a huge gap.
I'll run the same file on one of my desktops for comparison if you like.