My pup had a problem similar to this as well. I think the problem lies with him not knowing who is boss (the leader). There are some excellent sites that could help you communicate to the dog that you are the leader. A few things I did was, banish him from the bed or couch when he got aggressive, a firm 'Off!' and a gentle, but firm nudge will do. He cannot get back on if he behaves the same, then its off again.
Also try controlling his food more, give it to him for 15 minutes and then take it away. If he didn't eat, he will next time! And make him sit before giving him his food.
Teach him some tricks, like 'sit' or 'stay' (I can explain how, if you need me to) for a treat as a reward.
If he gets aggressive again, make him leave. Enforce this. If he doesn't leave, chase him out. If he doesn't get off the couch, put him on the floor and don't allow him back on for a few minutes (after he stops trying) and then call him.
Sorry for the long post, but this is just NB info that you need to make him a lovable pup.
