2003 cr250 bogging on low end acceleration

have a 2003 cr250r, had the bike for 3 years. run a airstriker carb, nedw 3rd clip,42 pilot, 172 main. been running this setup for years and never had an issue. new piston every year, and complete top and bottom rebuild last winter. we race motocross with it, ran 1st 3 races of the year and all ran well as usual. last race mid day the bike developed a hesitation on on acceleration, figured it was dirt in carb, took it apart cleaned it very well, hesitation was still there, re did carb cleaning and double checked float height and all was good, checked compression and it at 185psi.plug looks golden brown lie it always does, in in the lower to mid rpm range. checked needle and clip is still there and in same position we always have in it. kind of stumped. like i said we have ran the same jetting for 3 years and never had an issue. any ideas