Hello I put an OS 61 four stroke on my second airplane which is a Sig Four-Star 60 The engine starts easy and and runs great the problem I am having is when on the ground I set the idle so the airplane doesnt move until i throttle up. Then after 10 or 15 min. in the air when I come in for a landing the idle is way to high so I have to kill the engine and land dead stick in order to land it. I have checked the linkage and it is tight this happens ever time I take off any ideas what is going on?