I spent a few years down in South America and had the same experience. Speaking a second language causes you to think more about what you’ll say and really brings a magnifying glass to a stutter. Although, I noticed that the more fluent I became in Spanish, the less I would stutter. Now that I’ve lived back in the US for a few years, I’ve noticed my stutter in Spanish came back because I’m not speaking it as much. Also, I’ve noticed that even if I’m speaking and thinking Spanish fluently, the stutter still occurs sometimes because I’m thinking of how to pronounce words and have a good accent. So, best advice from me is to learn Spanish really well, to the point you don’t have to think about it as much. Haha sorry, kind of a sucky solution…