You mentioned he is a rescue... was he underfed or starved in his previous home? Our puppies have been food crazy since we got them and we read that it can be common in dogs who have been malnurished and starved. I know that most puppies can be food crazy, but our dogs would not even chew their food and were actually choking because they were eating so quickly.
Make sure he doesn't have worms or any other underlying health issues. If he is over weight, be sure to only give him the recommended amount and absolutely no food scraps or treats.
We trained our puppies to "eat on command" and it has helped them slow down and not eat so quickly. WE control what they eat, as the "alpha dogs". Practice giving him single pieces of dog food, and don't let him take it out of your hand until you give him permission.
It goes like this: put the food in front of his nose. When he tries to eat it, say "no" firmly". Do not let him eat it until you say "OK, good boy".
Eventually, you can do this with his entire dog bowl. Both of our puppies will sit calmly by their bowls of dog food until we give them the "OK."
Just a suggestion :)