You heard of Scroobius Pip? He's a rapper and poet with a stutter - also does a podcast which is pretty good going. Can't remember whether he had any tips but there's plenty of interviews with him. One thing he did say which stuck with me was something like "I think of my stutter more like an accent now; it's just my way of speaking." Edit: Here's one he did on stuttering: https://youtu.be/VommvzVm170 Edit2: Just on a personal note I'm big on hip-hop and I've found I can reel off a whole Skee-Lo song without any trouble when it's playing alongside but turn off the music and I'm hosed. I do find that almost talking rhythmically to the beat really helps though. If you've got your beat in one ear while recording and can tune into the rhythm that might make things run smoothly. Also if you're recording you can stitch together your vocals from multiple takes if you trip up on a line. I think even the pros do that in the studio, so no shame in it. I also find words to rap tracks naturally flow easier once they're embedded in my head. Maybe if you just keep rehearsing your lyrics you'll get to a point where you can lay it out in one take. Hope that's of some help at least. Good luck!