I am currently flying the MD-11F from Chitose to a city in Russia. But I seem to have a problem. I am cruising at M 0.82, and the autopilot is really struggling to keep the speed. It is going N1 102% in order to keep the speed. Before I was cruising at M 0.85 and then I decreased to M 0.82 and then back up to M 0.85, so then the autopilot went full throttle but still stayed at M 0.82. All the engines are working fine from my knowledge and the readings. This isn’t bothering my altitude or anything, but it could become problematic with the fuel. Any ideas? Is it a glitch? Is it normal?