Sounds like an RDSB issue where the station is broadcasting an alternate frequency AF and the radio is switching to, because the field strength of that AF is stronger than the one you are coming from. There are three fixes:

* You enable "LOCAL" mode, this should ignore those AFs broadcasted by stations which would switch to another station broadcasting a different program (it's actually more complicated, for brevity simplified). Not all head units HU offer this setting.

* You disable the AF-feature of your HU.

* KQRS should stop broadcasting this AF