Observations from a Newby

[RedMt Dave]

I am in the process of setting up and testing my trains on my layout which consists of all Bachmann EZ track. I have two large oval loops that are interconnected via an LCO #6 DCC and an RCO #6 DCC on the straight runs. The outer loop has 22"/22.5 deg curves and the inner loop has 18"/30 deg curves.
For my passenger train I purchased three passenger cars (85' Budd) from another manufacturer. I added weights to the passenger cars to bring them within the specs of proper weight for their length. They are being pulled by a Bachmann Amtrak Cascades #1400 locomotive.
Here are my observations:
Whichever passenger car is last, it will derail usually going through one of the crossovers. I have looked over the crossovers and cannot see any major issues. I've watched a few videos on YouTube concerning the issues with weak spring steel.
My freight cars run fine over the crossovers.
If I run the passenger cars on the outer loop with the 22"/22.5 deg curves, I will get an occasional derailment. If I run them on the inner loop with the 18"/30 degree curves, I have no problems with the passenger cars.
None of my shorter freight cars have any problems on either loop.
So, what am I doing wrong?
Will a more expensive passenger car perform better?
Should I consider replacing the spring steel in my expensive crossovers?
Thank you all for your insight and experience.