"93 Ranger Supercab

Ongoing situation. When I turn off the ignition, radio will continue to play. That is 95% of the time. Originally, I thought I had wired it incorrectly but every once in a while, radio will turn off as expected. Also noted that the key can be removed with engine running. Would this be strictly a lock cylinder replacement or do I have to look deeper?

 

Both lock cylinder and ignition switch were replaced but the radio situation remained the same. Checked the wiring and found a "filter & fuse box" inline on the power and ground leads. opened the box and found what appears to be a small capacitor. Before the box power is cut by the ignition but the output wires were still hot. Removed the box and spliced the wiring, All is good.