Kind of sounds like a rich needle setting. You might want to click the 'Every rider ... JustKDX' link at the top of this forum. It will have some good starting points for jetting. Read that first, but from memory I think Dave generally suggests a 45P and 155M, with needle in #2 from top (leaner than middle). With your altitude even that combination will likely be kind of fat. Keep in mind that your pipe, premix ratio, etc. can all have an influence. If you have the -30 pipe, you may need to go 1 richer on the main, from what I've read (personally I like my -35).
Also take note of the air box mods, if yours is still stock.