How do I fix bots giving incomplete sentences?

My bots start off good but after a few messages they start giving me incomplete sentences and also sometimes go off on nonsensical tangents. I’m not sure what settings I need to tweak to fix this. I generally don’t like messing with the settings as I don’t know what it might do. I’m using gpt 4 0613 because it allows nfsw chats and is cheaper.(yes I pay for it)