I have a similar problem to this. I think it's because we are overthinking what we are saying. We are interacting with the aim of getting people to think a certain way about us (i.e. to like us, find us not boring etc) rather than just being present and ourselves and responding in a way we would naturally. Someone told me to try focusing on what the other person is saying and take the attention from the inside to the outside rather than thinking about how you are going to respond. I also need to practice this.