2012 kw with isx down on power, hesitating.

hi i'm new to this site hope i post this right.So,we just bought a 2012 kw with isx supposed to be 500hp.besides being down on power, i have a problem with it hesitating. usually does it first thing after hitting the road. after typical warm up period in yard i hed for highway.from a dead stop up to about 7th or 8th gear(10 spd) it runs strong, then for about a second its like someone reached over and turned the key off.then it goes again but not nearly as strong.when running good it pulls about 35+ lbs of boost.after it hiccups i'm lucky to see 30lbs. other times it doesn't hesitate but pulls hard then the boost just falls from 38 down to 28 again right in the middle pulling hard. 1400 -1500 rpm. i know i'm not the only one with this problrm any help?