Locomotive stops

[PatBarr]

My diesel locomotive stops periodically on the track.  If I turn their speed control of all the way it takes off very fast.  Why does it stop sometimes on different parts of the track.

[jward]

Is the locomotive DC or DCC?
Does it stop in the same places every time or does it stop at random spots?
DO you have grades on your layout? If so does it stop on a downgrade?
DOes it mostly stop on curves? If you run the locomotive the opposite direction does it stop in the same spots as before?