Allegheny Again

Making the assumption that other trains run fine through this section of track, have you checked the pickup rollers on the engine?  I had a similar problem on one of my engines where the roller was losing contact.  I think mine was an internal connection, but I checked several contact points.  

Also, this is a 2 rail capable 3-2 engine.  Are your outside rails tied together.  This engine may have problems getting ground from one of the rails.  If you only have the ground tied to one outside rail, you could lose power.  What track are you using?

George

Try running the engine through the same section of track facing the other direction.

Proto -3    so no battery   . I think I would start (as mentioned)  by jumpering the outside rails together.      When it stalls out does touching a piece of  wire from the outside rail to any wheel  start it up ?

Thanks for the replies gents.

All other engines run fine, several are PS3 with the same features. This engine has been running on the track for over 1 year with no problems

Sounds like a loose pickup wire or a worn one.  Have you had the shell off the engine to give it a look? Things can wear or loosen after lots of run-time.