After increasing throttle to a setpoint, the throttle decides to slow down by itself. Throttle speed and bar indicators decrease without touching the throttle knob.  This is the second unit which is doing this. The first was replaced by Bachmann without any charge. The problem happens even when I am away from the base station. Anyone have this problem and able to fix it?

Just added a simple branch using 2 turnouts and 2 18" curve EZ tracks with rerailer +2 straights. My 2-8-0 loco cannot navigate the 2 curved tracks.  It derails on the rerails.  All Bachmann stuff including the loco.  What gives?  Loco runs fine on 18" curves without rerails around the rest of the layout.