I'm going to say again that if your are still looking at harnesses, then the Easy Walk is the way to go.
It reinforces some of the techniques that were mentioned above about turning around. Because the lead is attached to the front of the dog, any movement that you make besides going forward, is going to force the dog to turn back towards you.
Personally, though, I think harnesses are a last resort, or only to support on ongoing training.
I highly recommend going back to training. In fact, I would recommend group training, not individual. You want to teach your dog to interact with other people and other dogs.
I learned so much at puppy school in teaching my dogs to "leave it", "off", "sit", "look at me" etc. Any distraction can be met with a few basic commands.
The hard part is staying on top of these commands and constantly reinforcing them. I know that is where I have failed.
But there is hope. You CAN teach on old dog new tricks!