Sarah, I don't think this will help??
If there is an underlying problem with overload, the heat, ?wiring?.. Then unless this is corrected, then you will continue to have the problem.
The problem with intermittent faults, is that they are intermittent.. A minor, but undetected, wiring issue can be 'cured' by a very small movement of said wiring (for example).. This can be frustrating, and very difficult to isolate.
If your Central Station (controller) has been sitting in the sun, then it could very easily got to a point where it would shutdown.
The heat could have caused your track to expand, and this might have made a joint move enough to cause continuity problems..
Some systems require you to set the controller to 'zero' if there has been a fault.. No amount of knob-twiddling will make the loco(s) respond until this has been done. - I do not know if your controller does this.
If the loco stops, it suggests (possibly) a track problem roughly where the loco is.. If you pick the loco up, and move it a few feet back along the track, does it then run?
If you run a loco across one of your isolated joints, but have not installed a switch, then you could create a short and your system will shutdown / stop. - Different systems require you to remove the short, and possibly do other things (control to zero) before they will respond again.
Even on our modern, big systems, occasionally things do not respond as they should.. We then have to turn off either the throttle (intelligent hand controller) or the whole system, to reset it.