1. Since my J class was running erractic. I was told to remove the choke coils, Which I did. Is it necessary to add jumpers in place of the choke coils?
2. I also did not pay attention to the orientation of the plug from the tender to engine. Do the wires go on top or the bottom?
DC or DCC? You only need to mess with the Chokes if it is DCC. They have no effect on DC.
Erratic running is electrical pickup in most cases. Look at the tender pickups, wiring between the loco and tender and the drawbar wipers.