I hate my Step Dad he's a jerk and I really wan't to move in with my Dad, I have talked to my dad and he said I could move in with him but know I need to tell my mom and I'm way to scard to do that what should I do?

Is he a jerk because he doesn't let you do things, and is unreasonable, and the other lets you get away with most anything.
Or just watching out for you?

You can't just move in with your dad. Assuming your mother has primary custody, your dad will need to go to Family Court and petition for a modification of the custody agreement. Depending on how old you are and where you live the courts may or may not listen to your preferences.

I am sorry things feel this way. Your dad really should not have said this. It does not work like that. ( unless there is no custody order and no child support orders)

If you dad really wants you to live with him, he will need to hire an attorney and file in court for custody. So your dad will have to do more than just ask mom.

So now mom will sound like the bad guy when she says no, and you will say, well dad said it would be OK,
Even if mom tells you the truth about court you may not believe it, since dad said it was OK.