You said you have replaced the intake O rings, but have you checked the O ring underneath the starter? It seals the side of the crankcase during the crankcase suction phase of the cycle. If it leaks air into the crankcase, because 2 strokes always run very rich, the result is the same as if the throttle were opened further: more air plus plenty of fuel equals more revs. It won't have more power: it needs the rich mixture to produce full power, so leaning it off reduces power.
That O ring seems to be very prone to ending up out of position on Powertorques.
