When I first tried certain substances I had the same experience, but it fades. Even if you’re not using often or anything, the more experiences you have, the more your brain goes “oh I know what this is”. Then your normal brain functions come through, stuttering starts again. Just don’t fall for the trap of trying to chase Euphoria for the reason of easing stuttering. It’s a losing game and will make your stutter worse, especially in the case of stimulants.