Hi Imzick, welcome to the Uni. Firstly, here you have a wealth of knowledge to call upon. Secondly, your horse is talking to you - I have no way of knowing why he or she has a fear of being away from the barn but what I do know is it is probably because of human error. Something in this horses past has caused this behaviour. Right now he or she has no reason to trust you as their leader. So, step 1, Join up. If you do not have a Dually halter then order one - it's a brilliant tool. Once you have studied the lessons & achieved about five successful Join ups we can proceed. Update us on your progress & we can proceed. Have fun! Cheers, Jo.

Hi tmzick and welcome,
In addition to Jo's expertise advice, I would like to add: check the equipment, back and saddle area! 
I'm saying this because of your description that he becomes quite tense when mounted. It's likely to be a "mental" problem rather than physiologic, but it is always good to rule out all the possibilities or you efforts to make it better can in fact make it worse, if he feels or expects to feel pain when ridden.

Tmzick
To add a little more to what Jo and Kicki mentioned.
I have a Tennessee Walker that did the same thing with me when I first bought and started working with him. Jo mentioned something about his past. well I did a little background on my boy and found out that he had been ridden mostly by inexperienced riders with little or no knowledge of horses.
Monty has several videos on how you as the rider should approach your horse and the body language you need to make him not only trust you, but at the same time to relax, and lower your blood pressure, because that's the first thing he will pick up on when you mount.
I hope this helps some.

Thank you all for your advice! As I was reading Jo’s comment I had forgot to mention that I have tried join up a few times with him and he won’t join up with me ( I’m also new to this so it is most likely error on my part) but I’ve tried join up with him two to three times and he doesn’t seem to want to join up with me. 
Kicki, thank you for mentioning that as I do have some problems with his back and saddle area (as I again, I was going to mention but I’m working on figuring it out right now) because when I brush and curry his lower back area near his spine he flinches away, and he even does this when I curry and brush on his hindquarters near his spine. I’ve talked  to some people about it but they said it was probably the saddle pad, which we need new ones but we can’t get any right now. I want to get the vet out but I was told it was just the saddle pad so we are currently waiting to get new saddle pads before we have a vet come check him. So, for the meantime I’ve been busy with a lot of groundwork and getting him to trust me and used to me. 

Lastly, as Connie had said, we did get him for free from some good friends, who were inexperienced riders and they couldn’t handle him so we took him on as a winter project thinking his problem would be easy but it turned out to be months of work and I think I’m just beginning to figure out his problem. I will make sure to watch his videos and see what I can do with him! 

Thank you all so much for your advice! It really helped and I’ll looking forward to trying it! 

Hi. Can you describe how your boy reacts when you try Join up? Does he simply stand his ground & refuse to go away? Does he circle you but doesn't give you the 4 signs? Does he give you some of the 4 signs but not all 4? Does he not approach you when invited or does he not join you for follow up? You are correct in saying the likely problem is your use of Equus - unless your boy was hand reared by a human - in which case neither of you are going to be fluent in Equus! We an help you both with a bit more information. Cheers, Jo.

Hi Jo, He goes away just fine, as if he wants to be away from me and he goes faster and changes direction when I tell him to, but he doesn’t slow down unless he is near the gate and then I may push him faster unless we are on our last lap about to do join up. He will also give me all four of the signs at times and then other times he may give me two. Then, our other problem is when it comes to join up he will stop when I step in front of him, look away, drop my shoulders a bit, and begin walking toward the gate, but he refuses to come to me when I invite him even if I cross his body axis he will still not come to me when I invite him. 

Also, I’m unsure if he was hand reared by humans but from how he reacts to certain things I do and the whip ( which I only use as an extension of my arm for liberty ) I believe he was abused or trained poorly. 

Hi. I think the problem could be your adrenaline - practice keeping your breathing slow & controlled. It's easy to go to the round pen anticipating something may happen or worrying that it may not happen & horses sense that. Concentrate on slowing him down by using your breathing ( slower & deeper ) as well as removing eye contact. It does sound like he has a grave distrust so once you get Join up I would simply start from scratch - take him through the whole process, step by step. In the meantime there is something you can try. When you are grooming him run your fingers along his spine. Thumb on one side, index finger on top of his spine & second finger on the other side. Run your hand along his spine using your thumb & fingers to apply a little pressure. My Apollo had a hard life before he came to me & as a result had back problems. If I did this exercise he would drop down about a foot once my fingers reached behind the saddle area - clearly indicating discomfort/sensitivity. Apollo had 'kissing vertebrae' ( equine equivalent of a slipped disc ) but with treatment, from time to time, we had many years of mutual joy together. Study the Join up lessons, practice in front of a mirror to compare your Equus with Montys. Probably you just need to fine tune things so your guy can REALLY BELIEVE you're speaking his language. Cheers, Jo.

Thank you so much for your help! I do think my problem is my breathing and I do tend to anticipate what’s going to happen so I’ll start working on that. Like your horse Apollo, my horse does the same thing when I press behind his saddle area, he will drop away from my fingers. Thank you again for all your help and I can’t wait to work on this! I’ll be sure to fine tune my body language during join up so he can really believe I’m trying to talk to him. Thank you again and I’ll keep you updated on what happens!