Bike bogs when throttle is held wide

I have a 2003 CRF450R that i bought in June. When I'm riding it is a beast. The only time it isn't a beast is when i hold the throttle wide open in 5th gear. It will bog down quick and then be back at full rpms. This happens within a second and it doesn't stop unless I go down to half throttle. One thing that i find weird is that i always ride while listening to music, and when it bogs my earbuds crackle and sometimes the song stops for a bit. I've run sea foam through the bike and that didn't do anything. My friends think its a bad ignition cable. I originally thought it was the carb but now i'm confused. Any help will be loved!