Bought my Mazda protege today, it had a exhaust leak which I took right away to fix.after that it will not stay running

It's due to excessive back pressure and the leak although noisy was preventing high back pressure from building up in the exhaust ..I suspect a partially blocked Catalytic converter or if the leak was after the cat then your muffler is damaged

So ... whomever fixed the leak didn't check out WHY it had a leak in the first place? If I did that to a customer, I'd be fired. Totally agree that the leak was there for a reason.... possibly plugged or collapsed matrix in the cat.

It's not the end of the world as far as repair costs go ... a new Cat is lots cheaper than it was years ago ,,, and ,,, when that's fixed ,,, you will have a nice running car