Throttle problems

I installed the Camsim 797 and it flies very well except for the throttle, weather in auto or manual it will not slow down, the speed keeps increasing even with the throttles all the way back. makes it difficult to land unless you use speed brakes and then flaps. Have tried new panels,different autopilots,engine settings etc etc. I think I have solved the problem by changing the air file for a 777 air file. What in the air file is causing the throttle problem? You should not have to use the speed brakes to slow it down to around 220 knots, the throttle should be capable of doing that. It would be nice to know what in the air file is causing this. :-/