Did you neuter him? They calm down a lot after that, but little boy pugs, especially little black guys, seem to have issues with potty regardless life long, especially #2, it's like they have no control. The little black guy I had previously, would "bite" when playing for the longest time and had a tendency to badly react (think Cujo) to being yelled at and/or swatted. I think the person who had him before abused him to a certain extent because he was absolutely terrified of grocery size paper bags and newspaper being rattled. The vet figured he was about a year old when we got him and it took a very long time for him to calm down completely. It took me years to be able to cut his nails without an all out fight with squirming, squealing and trying to bite.
The one we have now just turned 5 and he barks at EVERYTHING, and will not hush, even if it's just a chuff at the end so that he can have the last word. He's also a car/other dog/duck chaser if he gets the chance, which is not often, but he does catch us unaware on rare occasions and jerks the leash out of our hands. He's also EXTREMELY protective of me and our female pug. He doesn't want any stranger coming up to us and has a fit, but then when the person makes nice, he's all for pets from them.