N scale 4-8-4 Runs jerky

[Chewey]

First one ran jerky, sent back and was replaced with a new engine. Second one actually runs worse. I have used the oil sent to me with my replacement engine and have cleaned both the track and pickup wheels. Other engines work just fine, any remedies, fixes or suggestions? Thanks!!

[ABC]

Try larger radius track, although you may be using the track that came with the set does not mean it is the best idea or that the loco will run well on the track provided. Get some N/S flex track and see if that doesn't help, because the curves could be the issue.

[Chewey]

Same problem on straight track, the engine will come to a complete halt, if I give it a little push will takeoff and run in a jerky motion a all speeds.

[ABC]

There still may be binding of some sort going on, and you probably over-lubed/oiled it by now.

[skipgear]

Start with, which 4-8-4? The Santa Fe Northern or the N&W Class J.

If it is the Santa Fe, they suffer pretty bad for poor pickup.  They only pickup power from the 8 driving wheels. It gets better with age. The best thing to do is let it run for a couple hours at moderate speed and let the axle pockets burnish and clean up. Adding tender pickups helps alot with these. The valvegear on these is pretty forgiving and doesn't bind without some help.

If it is the Class J, then I have to ask a stupid question, did you take the packing foam from between the trailing and leading trucks and the frame? There are small squares of foam that keep the trucks from bouncing around in shipping that the loco will still run with but it will cause problems with binding in the loco.