Have you tried plugging all the vacuum ports off at the carb? Just because something is new doesn't mean it's right. Try blowing air through all the openings, Jets, air bleed... of the carb & make sure air comes out somewhere. Pull the carb completely apart when doing this. Jets bleed to the bore, air bleeds into the bowl, etc. Look for any blockage in the jets. Main jet should be at least an 85. Turn the pilot screw all the way in before taking it out & count the turns so you know where to reset it, should be around 1 1/2 turns.