My Luke walks wonderfully beside me, but Beau still becomes enthusiastic when he thinks someone out there wants to fawn over him or he sees a doggie that he wants to meet.
I have a sensible or no pull harness for him that works very well for me. Make sure that it is tight enough though.
The ring that you hook his leash onto is on the front part of his chest. When he gets to the end of his leash, or when you pull him, he looses a lot of his body strength because his body goes sideways. If you have a regular collar on him, try stepping to his side instead of being behind him, and pull towards you. They aren't able to stay as strong in that position.
Can you go to a neutral area with your dog and a couple of friends that know him, and start off walking past these people with him, and get his attention somehow. Either call his name and get him to look at you, or if he's food motivated, as you walk by bait him with the treat and tell him what a good boy he's being.
Start doing this with strangers as well.
My Luke would growl and get his back up when I first got him. He does not like strange men! I always tell people to ignore Luke totally and to pay attention to Beau. Luke then goes up to them himself. Also tell people to hold their hand out to him and not look him in the eye. Luke does NOT like people going for his head. It takes a bit of work, but it's been 7 months now and on our last big dog walk, he went up to a group of strangers all by himself!
Huge progress!