How and with what is the best way to clean the track and wheels?

I have a n scale Bachman train that I only use at Christmas with our Christmas village.  I have Bachman EZ track.  Sometimes when I have the  train running it will stop at random places along the track.  Does anyone know if this would be the track or the engine.  I have checked and rechecked all of the track connections and they seem to be ok.  Any help would be appreciated.