When I turn off the autopilot on the Aerosim L1011 and DC10 the autopilot doesn't turn off immediately. It takes around 2 minutes for the autopilot to turn off after I switch it off. How can I get the autopilot to turn off immediately after I turn off the autopilot?

It's not the autopilot that is not responding immediately but after I turn off the autopilot and cut back on the throttle, the engine reduce their rpm's around 2 mintues later instead of immediately.