Confused pup with 4 previous homes Behaviour

Hi guys, I really do hope you can offer me some advice, because I'm feeling overwhelmed.

We've had our beautiful JRT x Chihuahua since he was 11 months old - he's 16 months now. We know he's had quite a few homes before us, so we understand why he has some issues.
First, let me tell you all the great things about him before we get into the not so great!
OK, so he's super smart, absolutely gorgeous! He's wolf sable in colour, with a huge fluffy tail! He never whines or cries, he fetches his leash, coat & harness when he wants to go for a walk. (Pretty annoying when he wants to go out in the middle of the night just to sit on the grass for a bit and have a look around!)
He's not possessive over his food, toys or anything else. He let's me brush his teeth, check his ears, etc and comb his fur. Before I open the front door and take him for a walk, he always sits nicely and waits. He's very playful and does this super cute thing where he play bows and bangs his front legs on the floor and barks at a toy, or a biscuit, etc.

RIGHT, now for the not so good!
He barks and lunges at vehicles, people (children and the elderly, too.) dogs, cats, birds, squirrels, his own reflection, items in shop windows everything basically! He lunges at our faces (fangs out!) when he wants something or he's excited. He shows his teeth if we try to kiss his face. (Which we are obviously not doing now.) He ever shows his teeth when approaching my husband's face to lick him. Which is our little dogs favourite thing to do in the whole world! He'd much rather lick his face than have a belly rub!
He has a few other issues with barking and peeing in the house after a bath, etc but I think the msg will turn into a book if I list all his naughty antics. The main 2 that concern me are the barking at people and the fangs out when he's near our faces.

A bit about his life with us might be helpful....
He's walked for 20min on the morning with me. 10min when my husband gets home on the afternoon. 1 hour on the park, on a long 12 metre training lead. (lots of running to burn some of his energy off.) then 4 more 10 min walks throughout the evening.

Chicken, steak, lamb are of no interest to him when he sees something he wants to chase. I've tried and tried working from a distance from the distraction and getting closer, but there has been no improvement in 5 months of having him.
He has a round Kong toy and has lots of play time with us, but his energy is endless.

When he shows his teeth, he doesn't growl and there are NO other signs that the fangs are about to make an appearance. No lip licking, turning his head away, yawning etc. Just straight to the pearly whites! We don't smack him - we've never smacked any of our dogs. We just tell him no, withdraw attention or put him out of the room... But he's getting worse. Now, he shows his teeth and bites (not hard enough to break the skin) when he doesn't want to do something, or we try to pet him. Time outs frustrate him and make him worse. If we ignore him he thinks he is getting away with barking his head off, which he kind of is!

I don't think it's true aggression and I don't think it's a submissive grin. It's more like he's anxious, stressed or just bossy! (??)

I googled SO much information about it over the last 5 months and I can't find anything that fits the description of his behavior.

I'm sure I'm missing some important information, but this msg is pretty long already.

Has anyone out there experienced this toothy behaviour in the same content? I hope someone will reply because we are scared this will continue to get worse. He's started showing his teeth more and more lately, too.

Also, some help with the barking /lunging would be great. Everyone looks at us like we are bad doggie parents that can't control their dog. The latter part is true.

Any advice would be appreciated .

Ava you all must be exhausted and frustrated
Sadly I can’t offer any advice that I think would help other than get in touc( with an experienced trainer
I am sure someone will come along and help you in the mean time.
I will be following with interest and hope you get some positive comments

This may seem a strange question, but I do have a reason for asking it

What do you feed him? Is this behaviour worse up to a couple of hour after feeding?

Is he entire or castrated?

Thank you

Good question! He won't eat dog food, so he has fresh chicken, lamb, beef or turkey (He's costing us a fortune! Lol)
He has some cat food from time to time, pedigree milky bones, chicken jerkys and pedigree denta stix. That's about it. What he eats one day, he won't eat the next.
He's castrated. We had him done after 6 weeks after getting him. The barking at people started about a week after getting him done.

Oh and his behavior doesn't seem to relate to when he eats. I will definitely look out for it though, I could be wrong.
Also, he'll have about 4 days of being less toothy and barking at about 70% of people we walk past (instead of 95%!) then it all starts up again.
His tail is high and he looks very confident on his walks, BTW. So I don't know if it's fear or he's just a bossy jackchi! (He looks more like a mini German Shepherd X with a dachshund!)
He pee'd on the bed after his bath the other day, too.
(Sorry for all the random info! :/ )

keep a food diary. List everything he has to eat during the day and also list on a scale of 1-10 what his behaviour is like on that day. It may not be related, but food can and often does create behaviour issues if there is an intolerance to one or more food item.

Also, how do you balance out the meat to make sure his nutritional needs are met?

When he barks/lunges ,what do you do ?

I call him and offer him fresh meat or walk him away. The food only works if we are a long LONG way from the dog or he hasn't seen in, but I have no chance getting his attention if I get any closer - I've been trying for months.
BTW, he's not aggressive towards other dogs, he just wants to sniff, then play, but it's rare we bump into anyone who wants to let their dog play with a lunging, banking crazy dog!
If we have to walk past people on the street, I have to hold him back, because he barks and lunges at their hands.
It's like he's never seen the outside world before. He barks at everything.

We had a German Shepherd cross for 17 years. He was an incredible dog.

That's a great idea.
I might do a full daily record of everything, from the moment he wakes up.
Most of his food (the dry stuff) is there for him to eat at any time. He has meat treats way too often and I know I'm making the problem worse by giving him so many treats.
I lost my wonderful Yorkie 3 years ago and I'm still heartbroken. I don't know if he's picking up on that too.

I took this pic today at the park.

He's a real cutie

Thank you .

I would find a quiet spot where you can just "Sit" and have him "observe" at a distance he is comfortable with, Parks, outside supermarkets/schools ect: When he does see someone or another dog you have to distract him before he kicks off ‘by playing a game or doing some training exercises, you have to be more important and fun to be with.

He is lovely - such a cute face!

This is a great idea. He actually loves to sit in random places on the park and just watch the world go by. I think I'll let him sit for much longer and try to get his attention on me. schools etc are also a great idea I can keep him at a distance and he can watch.

I could say the same for your little doggy. He's gorgeous.

Thank you. That was my beloved Pereg - she has been gone nearly three years now but I still keep her picture as my avatar.