I subconsciously mimic the lip movements of others,is there a name for this?how can i stop?is this averbal tic?

It's a processing disorder. While your brain is processing the information, you mouth it to retain accuracy and allow it to do what it will at it's own pace. If you only do it when excited, it also could be possible that it's a habitual mechanism you use to keep your mind on something you deem important - in light of your ADHD.