Since loading the Lightnings I have had intermittent problems with lack of power. Despite starting with all switches on and starting engines normally I cannot reach higher speeds than 250 knots despite the afterburner effect showing and 100% full power on engine instruments. If I attempt a climb after cleaning up the aircraft I will stall. This occurs with all Marks and can happen if its the first aircraft I fly in game or the last. I have calibrated my throttle , a Saitek x52, and redownloaded replacement files.This is happening about nine out of 10 flights. No other aircraft in my game, Prepar3d 4.5, suffers this problem. Can you help please?