I used to walk a friends dog, he used to pull all the time, until i spent some time with him - never pulled with me again.
He also used to race you up the stairs, especially when 'grandma' had a basket of washing and got told off a lot for that, i stopped that and he never beat me up the stairs!
All you can do is try your best, like Al says, if he gets it, he'll always be good for you, hopefully you can pass that back on to his real owners.