Re: throttle problems
first trouble shoot your controls--take the hood off the motor, and watch if the motor's working move with the throttle.
If the parts are moving like they should, are they connected correctly to the linkage to the lower unit?
After that, yo umay have issues inside the lower unit--the gears and clutch dog in there. major problem, hard to fix.
If the motor's in neutral, and off, can you spin the prop by hand? If it's in gear at the throttle, and off, does the prop no longer spin?
I think you need to re-read your post and be a little clearer about what's going on.