Starts, then doesn't start, then starts again.

So my dad and I rebuilt my 73 dart about 3 years ago. Shortly after that I joined the military and left it in California. Over the past two years I've gone home several times and never had a problem with my car. About a month ago I got a friend of mine to trailer it to North Dakota where I'm stationed at. Had no problem getting it off the trailer and driving it into the garage. The next day it started up just fine and I drove it to get gas and then to a friends house. After Spending about an hour at his house I went to start it up and it just tuned over but wouldn't fire. Come to find out the ignition module was bad. I replaced that and didn't have a problem with it for about 2 weeks. I let it sit for about a week and then decided to take it out but when I went to start it the battery was dead. I figured it was just an old battery and that was my cue that I should be looking into getting a new one but didn't pay much mind to it. I got a jump from my roommate but it took a little bit to fire but eventually did after 10-15 seconds. Again, I thought nothing of it. Drove it to my friends house and parked it and it sat for the majority of the day. Then I went to leave and it turned over a couple of times but in a matter of seconds the battery was dead so again I figured I would just drive it home and wait for payday to come around so I can pick a new battery up. But then I had my friend hook up some jumper cables and would not fire. I didn't have a lot of time to look more into it because it was late and I had work in the morning so I put the car cover on it and left it at my friends house. I didn't touch it for a whole week and finally got the time to go take a look at it on Friday. I was going to use a multi-meter to check and see if all my connections were good and what not but again my battery was dead. I had my friend hook up some jumper cables and I turned it over and to my amazement it started right up so I took it home. I figured maybe it was flooded before or something of that nature. My roommate was working on his car so i decided to pull it out of the garage and park it in the driveway s he had more room to work and so I did just that. But when my roommate was done and I went to start it to pull it into the garage for the night again it didn't start. So that's where I'm at right now. To be honest when my dad and I rebuilt it he was pretty much the one doing all the work and I just handed him tools but I knew getting my car to me was going to run into problems sooner rather or later and this is one of those situations. Any help would be greatly appreciated.