If you are relying on rail joiners without solder between the sections of flex track, then it is possible that the particular section is not firmly spiked to the road bed. The weight of the locomotive can cause a slightly loose section of track to move up and down and possibly break contact.
You can test the next time it happens by gently pressing one (or both) rails between the stopped loco and the next set of joiners--before and behind. If it starts right back up, then that is the problem.
Even if soldiered, the joints can still break loose.
Make sure the wires from the tender are firmly plugged in. If one of the plugs is loose, it can cause the loco to stall periodically.
You may have a loose rail joiner that causes the Bachmann steamer to stall even though nothing else does.
i dealt with the same issue on a previous layout at first i thought it was the loco then i thought it was the dcc system. after pulling out my hair for days i inspected my track with a fine tooth comb. and im not sure what type of track you have decided to use but i was dealing with flex track. i found that the track can be slightly twisted in some areas and it doesnt matter if its a straight or curved section of track. the track only has to be twisted and be off by millimeter and it will break the contact between the rails and the loco wheels just enough to stall the train. one thing you may try, if this is what is causing the problem, is to take a pair of pliers and try to twist the track back to its true position. however be easy or you could destroy the track. otherwise you may need to replace that particular section and make sure you tack it down well when gluing the track to keep it true and flat. hope this helps, good luck.
Are you sure the loco shorting out or is it just stopping? Is it doing it on straight track or on a curve? Does the loco restart on it's own or does it have to be pushed a little? DCC or DC? I have a Spectrum 2-8-0, runs good with DCC and sound. Each of the driving wheels on the loco and some of the wheels on the tender pickup power. I would look at them to see if the wipers are clean and making contact with the wheels. Could there be a slight dip in one of the rails in the area where the loco stops causing some of the wheels to be suspended above the rail and not picking up power?
You have a pic of the area in question?
Springfield PA