I was recommended to try this thread for my issue. I have a 2019 Expedition - about a year ago (~30,000 miles) it started making a surging noise - like whoop, whoop at 1600 RPM. The engine has to be under slight strain - either up hill or towing the boat. If I have the boost gauge displayed you can see it fluctuates back and forth in time with the noise (the gauge flutters from 1/4 to 1/3 of full scale). If I can hold the RPMs at 1600 it continues to do this. If I accelerate or decelerate even slightly the noise stops, the boost gauge is steady. There are no other issues at any other RPM or load situations. There is no loss of power when this happens, it just sounds odd. I would say the noise comes from the left side (drivers) of the engine. Originally, I though it was a tire or mud flap vibrating in the wind until I saw the boost gauge respond like it does. Normally, the engine runs strong, accelerates fine, has no other obvious issues. Also I have an AFE Magnum Force Performance Cold Air Intake System and a Magnaflow Cat-Back Exhaust System installed.