issue

[sickcat05]

hey im looking to see if i can diagnose my problem i have a 05 arctic cat sno pro 800 mod and some times when i get ready to go it revs up to 4500rpm and goes no problem but on some ocasions i hold the throttle it climbs to 3500 or so and sounds like its bogging down almost like its stuck...
can anyone help me with my issue
thanks