I able to print a part that takes up to about an hour and a half before it stops, so am thinking this might be a heat related problem of some sort. I am trying to swap the A4988 drivers with DRV8825's on the Ramps board to see if my problem goes away & the printer is now printing the part what looks like half size. I tried keeping the default steps the same as the A4988's & also doubling them and either way the part prints what appears to be half size. I also noticed the Z axis has a little bit of vibration rattle to it while & X & Y axis movements seem smoother. I have Vref Voltages set to .4 to .42 on the DRV8825's. Is there something else I need to change in the firmware that I am missing or do I also need to change something in Pronterface or Slic3r 1.2.9? The nema 17 motors are type 42bhh48-151K-24B.

Here are the only settings I changed in the Marlin firmware.
//For A4988 drivers
#define DEFAULT_AXIS_STEPS_PER_UNIT {80,80,4000,865}
//For DRV8825 drivers
//#define DEFAULT_AXIS_STEPS_PER_UNIT {160,160,8000,1730}