I have moved up from flying electric to gas. I now have an avistar. I really love the plane. I have one problem. when I pratice landing, I turn the plane around and go back to the end of the runway.When I throttle back up for takeoff, the engine seems to lose power. I have to do a runup for about 30 seconds before I can takeoff again. I have the stock la40 engine. I runs fine when in the air. Is the tuning not right or do I have another problem