Engine stalls while driving at idle?

Back in July, I had a couple instances where my vehicle would stall at idle: the first time it took about two to five minutes for it to happen. The second time, later in the same day, it only took about thirty seconds for it to stall. Then it was fine for a couple weeks until it stalled as I was turning onto a street going about five mph. Then I started it up and drove it until I was at my destination and it ran fine. I thought maybe it was because it was due to some bare wires behind my fan speed control knob, so I turned the fan off completely (this was back in the end of July) and it ran fine since then up until today still with no A/C fan on. I was playing a CD (do not know if this will help or not but I mostly play music through my aux cord and this was the second time I have played a CD since this happened, and the only time it stalled doing so). It stalled going about twenty mph and I was braking due to traffic. Through my hazards on for two seconds, started it up and off I was. It ran fine up until I pulled into the parking spot at work as it stalled again, still playing the CD. On my way home, I switched to listening to music on my iPod through the aux cord and it never stalled. I have seen similar posts suggesting it could be a faulty crank position sensor or a bad fuel pump relay, so I am thinking that is it. On a side note, the odometer reads approximately 144,000 miles but that is only approximately 78,000 miles on the engine I had installed two years ago to replace the original one that quit running. Do not know if that will help with this but figured I would specify that. Any suggestions would be greatly appreciated. Thanks