5.4 drops to idle or dies......why?
Purchased new, '06 5.4 4x4. The truck has 120,000 miles on it. Nothing has ever broken, runs fine 99.9% of the time. New battery recently. Throughout the life of the truck there have been times at low speeds or coasting where the engine would either die or idle only. This has never happened at high speed or when the engine is under a load. This happened at appx. 15K, 40K, 60K, 80K and of recent has happened three or four times in the past month.
Typically the engine acts like it has died. I pull over to the side of the road and see that it is still idling smoothly but idling only. Pressing the accellerator doesn't rev up the engine. In each instance if I shut the ignition completely off, wait a second and try to restart, it will fire up immediately and operate as normal. Smooth and powerful. Smooth idle. I have never changed the fuel filter. Any ideas? There are no codes. Once refired it runs fine until the next time it decides to do this. Happens with full tank all the way to low fuel supply. The truck is still stock and nothing has been replaced except routine maintenance items. Original plugs. Thanks, Jim