You can either fix it mechanically by adjusting the linkage so that the throttle is full open when the servo just reaches it's full throw, or you can set the end-point from within your computer radio menu for the throttle. If you don't have a computer radio, then you are stuck with doing it mechanically. But, as said, it has to be done or else you chance stripping gears in your throttle servo.

This goes for other servo's and linkages on your planes as well. Binds can drain batteries very quickly and can cause problems with stripped gears very easily by breaking teeth off of the gears when stressed like that. The servos should move freely from end to end without any binding from linkage or from control surfaces. The primary ane preferred way to fix this is mechanically. You can change the holes that the clevis or the connecting rod on the servo end is connected to either on the throttle arm or the servo arm. Closer in on the servo end will shorten the throw. Further out on the throttle arm will effectively do the same thing.

Also, keep in mind that this may not be the cause for our jitter. It is a cause, but there are others. Examine this one first because it is the most obvious.

CGr.