This is a twofold problem really ....
First is the proper way of healing when he is on a leash and the other is
his distractility
His "doggy ADD"
As far as his healing on the leash with you correctly
if he pulls you stop .... STOP
do not let him pull you
and you make a slight yank on the lead
when he settles down and again you start again
and not before
The distractability is handled by acclimatizing him to things that get him crazy
take him out after he's better on a leash with you
Have treats ready
when something you know is heading your way stop distract him by calling his name
You can even block him by getting between him and the distraction
show him the treat and let him nibble at it in your hand but don't give it to him until the thing that makes him crazy passes