225 starts but won't run

Yup

In all these cars, you have a separate contact on the ignition switch which is hot ONLY in start. This feeds power only one place---direct to the coil. Ma calls this "IGN2" and it's traditionally brown.

When you release the key, the ignition "should" get powered from "ignition run" or IGN 1" which is traditionally dark blue. If the resistor is bad, you won't get power when in "run"