The idle position is usually set with a pressure gage attached to the trans. You pull it out just a little until you see the pressure rise and that is the idle position. Without the pressure gage just pull it out about 3/16" of an inch.
The geometry at the throttle has to be correct, that is to say that the ratio of the cable travel has to be correct for the given throttle movement. A lot of adjustment to shift points and overall feel can be made with an adjustable throttle crank.
What injection system do you have?
Be advised that an improperly adjusted TV cable can ruin the trans in a very short time
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Vince