Vanessa, see if he will respond to a squeeky toy. If he does, you can remove the squeeker from the toy and keep it in your pocket as an attention-getter.

Put a long-line on him when you are in the park; this gives you a way to get him if you need to and will give you the means to control him.

Here's the one I use: (purchased here)
http://leerburg.com/1061.htm

It doesn't have a loop at the end, so I tied a knot in mine to have something to keep my hand from sliding off the line...

From your post where you said that when you run he will chase you, I think this may be a mixture of prey drive and frustration.

Your dog does not know what to bite and when to bite, so he is biting you instead.

When you go to the park, try tying a long, thin (fabric wise), piece of towel to the end of a 4-6 foot leash. Put him on the long line, and drag the towel on the ground giving it a quick tug to entice him to play with it. When he has gotten it, don't play tug right away, just hold the end of the leash and let him carry it.Eventually (maybe even in the same session) he will start to pull it from you, let him pull while you walk forward and he pulls back. Don't give it completely to him, you still want to have control over the object. Keep doing little "tug" sessions with the towel until he gets it. Then move to a soft tug with a handle and attach it to the leash, start over again. If he goes for you or your boyfriend, use the towel or the tug to re-direct him to a tug session.

He needs to LEARN to be re-directed by the tug.

I will try this. I think we made a mistake in giving up on playing with him and his toys. It always seemed to lead to him biting us and showing no interest in the toy so we just started avoiding the situation. As evidenced by our escalating biting problem, this doesn't work. I'll try to play with him a little more and work on redirecting back to his toy. I really have to work on remembering this is just a puppy who wants attention and play time. It can be hard when you have a 70lb dog clamped on your forearm.

I know the crate should not be used as punishment, but if he just won't give up on biting is it ok to put him in there for a time out? If I let him, he'll spend 20 minutes trying to bite at me. After many attempts at tieing him off to the door, letting him calm down, coming over with a toy, but just getting the biting again I get tired. At this point I usually go get a treat while he's tied up and then come back and lure him into his crate.

You don't need to make the crate a punishment in order to use it for him to calm down.

When he is excited and jumping, and you are getting frustrated you need to separate yourself from him so that you do not take out any frustration on him. So when he gets to the point where you feel your frustration level escalating, take a deep breath, walk him calmly to his crate, put him in and calmly walk away. Show no emotion to the dog and don't even talk to him. If you have to lure him in his crate, do so without words. Take your time to calm down, then try again.

Just stay impartial to the crate and don't just throw him in it when you are mad, then it will just be like any other time you put him in his crate.

 Quote: Vanessa Fullerto

I know the crate should not be used as punishment, but if he just won't give up on biting is it ok to put him in there for a time out? If I let him, he'll spend 20 minutes trying to bite at me. After many attempts at tieing him off to the door, letting him calm down, coming over with a toy, but just getting the biting again I get tired. At this point I usually go get a treat while he's tied up and then come back and lure him into his crate.

There's nothing wrong w/ using the crate as a calming-down strategy (for both of you).

You can also use obedience to redirect his biting. ie Move right into a session of marker training when he gets mouthy, especially if redirecting to a toy isn't working...

Tiring out his brain (with plenty of short, upbeat marker-training sessions) is as importnat as tiring out his body...

Have you considered using a basket muzzle on this dog until you can properly train him? It would sure save your arms (and your patience). (They make them to fit Boxers).

 Quote: vanessa fullerto

The first time he brought a female boxer to test Chief's reaction. She took a while to warm up to him and even snapped at him which apparently is very unusual for her. The trainer said that though Chief was "playful", he was acting very dominant and just kept at it. He said we should be wary because he will probably piss other dogs off even though he wants to play and not fight.

Did anyone else not think it was odd that the trainer's first session with the new owners was to bring a female boxer to the session? I really don't understand what the point of this would be. They'd only had the dog for a week, shouldn't the focus be on bonding with the new owners & learning (or re-learning) obedience, not seeing how the dog reacts to a female?

Even though the dog is 14 months old, I think treating it like an owner would treat a new puppy would help a lot. Focusing on things like crate training, pack structure, marker training, and overall setting the house rules should be a priority just like it would be a for an 8-12 week old pup.

So frustrated right now. Chief is starting to refuse to go "potty" when I take him out back. I just spent 20 minutes waiting for him to pee in the backyard and he kept trying to lay down. I'd get him up and walk him to a new spot and he'll just stand there and look at the ground. He doesn't care if I ignore him. Ed mentions in the Pack Leadership DVD to always wait and make your dog go before you come back in. Is there a chance he just might not have to go? Is this an example of him trying to assert dominance? I'm very confused how to handle this. Should I bring him back in and put him in his crate or leave him outside tethered to the door and then keep trying every so often?

How long had it been before his last pee?

Please don't get frustrated over potty issues. That's something that frustration/anger/anxiety makes much much worse.

Remember that he is still new to you. That means that he doesn't yet understand your desires and you don't understand his schedule and body language.

What I would probably do is take him outside frequently (but not for 20 minutes), take him to the spot where he last went so he can smell it, and when he finally does have to go, and does, praise and party.

 Quote: vanessa fullerto

Is there a chance he just might not have to go? Is this an example of him trying to assert dominance?

My opinion would be (1) yes, and (2) no.

Even though there are often wires crossed and frequency misunderstood, IME, normal adult dogs want to potty outdoors when they have to go (unless they have had the misfortune of having been "trained" to go indoors by not being given opportunities outdoors).