so i was walking around in the wasteland and suddenly this NCP MP comes up to me out of nowhere and says something like "You should have payed your dues no one fuc** with the NCR and gets away with it" then he attacks me and all other NCR everywhere go hostile. I had idolized rating with the NCR and I dont know why I got attacked by this guy.

That happened to me as well, I'm pretty sure it's got something to do with completing that quest for the artist in the strip. It doesn't make very much sense why this mp does this though. I could kill him without a faction hit because there were no other ncr around at the time. It's probably best to outrun this npc if he spawns around other ncr. Console killing isn't safe because sometimes the game registers you've done it.