I have a couple questions.
EXACTLY how old is he... My oldest boy didn't get interested in potty training until he was 3 1/2. He has it completely under control now at 4 yrs.
Is he wearing pull ups? Pull ups are a glorified and more expensive version of diapers. The thing that really "got thru" to my boy was having him pick out big boy unders and then him wearing them. They are less constrictive than pull ups and diapers. They let the juices flow... I know its gross... But there is a different feeling to poop in unders and poop in pull ups. It will take some time, but just tell him that (lets use diego as an example) Diego doesn't want poop on him. If diego does get poop on him then we have to throw him away. (what would you do if someone tried throwing away YOUR BRAND NEW STUFF?...)
There is also the way that he is talked to. Do not call him the baby anymore. He is only big boy... and talk about what big boys can do... They can ride bikes with training wheels, swim with floaties, ride horses, etc... pick things that you would let him do and that he WANTS to do. Talk about how big boys do it... Talk and talk and talk. You know he has the ability... Its just a mental thing now. Really act disgusted and disappointed when he goes in his pull up... Talk it up and have a party when he goes in the potty...
Keep trying, but don't become really strict on it until he's closer to 4. Wouldn't want him doing it as a control thing.
Good luck!!