So you got this far in your academic career and you are questioning your ability to succeed? I have a stutter too and I am consequently going to start an MBA program next month. I have many doubts about my ability to succeed but you really have to relish your previous successes and take that as motivation! If you received a bachelor's degree and did relatively well then there's nothing that will hold you back! Just keep on working and preserving and you will be successful just like the other famous stutters out there!