You call a function, delayMicroseconds(), that is NOT defined in the code you posted. How can you expect that to compile?
If, by some miracle it does, how can you be certain that you are sending a 0 to the function?
Where's the facepalm smiley when you need it?
Sorry, maybe this is the wrong place to have put this, I haven't written c code in 20 years and this is my first arduino project. If the output is looking at the pot input how does it " never stop".
I'll flip that question back to you. Look at your code, and tell me in detail how you think the pot will stop it. Just "looking at the pot input" isn't enough, you also need to do the correct thing with the value. Because I can assure you (along with MorganS) that it will never stop the motor. If you think it will stop it, you are either not thinking it through enough or are horribly misunderstanding something. In either case, something needs to be cleared up.
What pin is #13 connected to on the motor controller?
EDIT: Hooray for taking too long to write my post!