Did you plug in HDT after the flight and check what the screen said?often what you are describing can be caused by exceeding pump limit, after which the ECU will struggle to manage the pump effectively resulting in delayed deceleration. The screen will flash 'PUMP LIMIT EXCEEDED' after the flight but before the Rx is switched off. you need to check your fuel system for restrictions then go through the setting pump limit process, and set the limit about 20% above the highest pump Pw used in accelerating to full throttle.