What would cause a 1998 Nissan 200sx to do this?...?

Yesterday the car wouldn't crank because the battery cables were loose. I fixed that and let it sit until this morning. Then I went to crank it and it wouldn't crank. And when I tried to crank it, a little smoke was coming out of the tail pipe ( I was told by my friend) and It wasn't the battery because it was trying too easily to start. I had my friend take me to work because I was in too much of a hurry to mess with it. I came home and it still wouldn't crank. So as I was trying to crank it I pumped the gas pedal and it started right up. But then wanted to die down on me so I kept pumping it for a few seconds then it was just fine on its own. I turned it off and then started it again and it started just fine several times with no problems at all just like normal. What happened to it? Should I ignore it? Should I have something done to it?