If a few of your bots are having randomly low GPH, here are a couple things you can try:
A) Turn off plugins or remove the plugin from the Scripts/Baneto/Plugins folder then close wow completely and reopen
B) Switch layers, easiest way to do this by your self is to go to Thal and switch War mode on or off, also I like to have 2 bots on each server that I farm, to help with this.
C) Switch to an old area zone such as Ohn plains, Azure, or Waking for a few hours, then you can move back to Forbidden
D) Check to see if your deaths are high, try to find out reason behind and try to fix it; such as equipment, enchants, rotation, settings, talents, etc.
Try these out see if they help @here