Band 5 Interference is too high. If your LIMIT4 is the default value then it corresponds to an interference level of better than -88dB.
Best way is to check the nearby sites for interference too. [Probably it is external interference due to Jammers or Military transmitters]. See if you can pinpoint a possible location using Interference in the area.
But Spectrum Analyzer is the best solution. Coupled with a directional antenna, you can dig out the source of interference. [Do remember to hunt for interference in the hours when ICM band 5 is visible in stats]