The problem I'm having is pieces of dialogue will just cut out an example is at the start during the execution when the guy says "For the love of Talos shut up and let's get this over with" it comes out "For the love of Talos shut up ____ ___ this ____ with". The words aren't actually skipped over it just goes silent. This happens in a lot of conversations and ambient dialogue across the entire map.

I've tried doing a fresh install with no mods but that hasn't helped.

As for the couriers they'll run up to me and say they've got a letter but no dialogue will start and then they'll just follow me everywhere. I've been able to make them complete the deliveries by fast traveling back and forth between that location and one far away but it's pretty annoying.