It depends on a position that you’re applying for. If the job requires a candidate to have excellent communication skills, then you should NOT mention your speech difficulties and speak in the way that you feel the most comfortable with. But if the job doesn’t require much of a speech perfection, then, stay focused on the skills that you are good at, boast about things you can do really well at this job and do your best to forget about your speech quality. I wish you good luck with your job interview;-)