I have a 5.4 24v engine in my 2004 F-150 that has a humming noise sometimes when I slowly accelerate. It sounds like a four barrel carb kicking in but no extra power. If I let off and accelerate again it works fine. If I push the peddle down farther it passes and accelerates fine. I have cleaned the MAF sensor with spray cleaner no change. I pulled the throttle and spacer off and cleaned with no change. Sometimes the engine will increase 200 RPM's and back to normal over and over again(8 to 10 times). Any ideas before I throw in the towel..

 

You may have the pedal position switch on the accelerator pedal going bad....

Could also be the throttle body assembly also going bad.....

Try changing the fuel filter?

Any dtc codes?

 

Changed fuel filter last oil change. No change. Is their any way to check the listed parts before replacing.