Why do I only stutter rarely when I am drunk, and never stutter when on MDMA?

Why do I only stutter rarely when I am drunk, and never stutter when on MDMA? And how can this be carried over to sober states? I find myself drinking a lot to reduce anxiety and stuttering, so it would be great if I could reach this point without needing to intoxicate myself. I'm guessing the depressant effect of alcohol might relax me enough to stop nervous stammers, but that doesn't explain why a stimulant like MDMA not only mitigates stuttering but extinguishes it.