Various Problems...Car wont start

This is what happened. One day I was coming home from university, like an hour drive, and the car was low on oil. I turned it off that day, got some oil to it and the next day when I turned it on it sounded weird, kind of like a harley motorcycle. I guess one of the cylinders was not working but after reving it up it worked normal. that was like a month ago and It did the same for a little while.
After one week it was back to normal and worked perfectly so I took it on a trip and drived for 3 ours without any problem other than one of the wires to the starter was loose and it didn't crank when I tried to restart it, however it did start by pushing it. I got the cable back in place and everything worked fine while I was away from home.
On my way back home the car turned off and it was very hard to get it back on. I managed to start it and kept going until it over heated so I stopped and it was the heater core hose that had a hole due to the clamp. So I cut the hose and put it back on but it came loose again and all the coolant fell on the floor. I called the towing service and got home like that.
I replaced the hose and the starter since it only had one bolt to it (idk why) and it broke where the bolt goes. Now the car tries to start, the engine turns but it just doesn't start. Apparently the third cylinder was not working at times since the first time I ran it with low oil.
I need help since this is my only car and I do not have much money nor time to put into it....By the way this is a D15B7
After one week it was back to normal and worked perfectly so I took it on a trip and drived for 3 ours without any problem other than one of the wires to the starter was loose and it didn't crank when I tried to restart it, however it did start by pushing it. I got the cable back in place and everything worked fine while I was away from home.
On my way back home the car turned off and it was very hard to get it back on. I managed to start it and kept going until it over heated so I stopped and it was the heater core hose that had a hole due to the clamp. So I cut the hose and put it back on but it came loose again and all the coolant fell on the floor. I called the towing service and got home like that.
I replaced the hose and the starter since it only had one bolt to it (idk why) and it broke where the bolt goes. Now the car tries to start, the engine turns but it just doesn't start. Apparently the third cylinder was not working at times since the first time I ran it with low oil.
I need help since this is my only car and I do not have much money nor time to put into it....By the way this is a D15B7