some mystery in your descriptions. Think you are saying you are operating the throttle lever mounted on a center or side console. (I'm with flyingscott -- think you are probably mistaken about the throttle plates. Otherwise, Jimmbo gives good troubleshooting advice.)
I'll guess you are operating the throttle in your driveway, and getting only to fast idle. You must have the air cover off to see the plates, and guessing you are checking with the motor off and in neutral (throttle won't advance beyond fast idle unless in gear, and plates would not be fully open). And If you were running, I think you would hear that the motor was nowhere near WOT, although that probably begs the question.
Having said that, don't run it on muffs above a high idle.... If you want to check throttle plates, put it in gear and check with the engine off. You may have to turn the prop a little with your foot to get the gears to mesh.
