25 hp johson will run fine to half speed?

over half throttle will not speed up acts like its missing ,have cleaned carb, anyone have idea of problem?

Try this post over in the mechanics corner some good mechanics there, may be coil or needle stuck was the carb recently rebuilt ?

First I'd replace plugs. If that dosn't fix it my next check would be coil.

I had one do this , overheat alarm wire broke off .