I dont know if you got this figured out yet but it the acceleration setting in the Sailfish firmware. The ReplicatorG version that ships with the Flashforge SD card is not fully compatible with the installed Sailfish firmware. You should download the newest RepG from thingiverse.

The stair step happens because of how fast the extruder changes directions. You may have noticed a heavy vibration almost like the printer is gonna break itself. The new RepG has the fix for you.