99 expedition runs fine then every so often under a load acts like ignition module is breaking down when gets to operating temp.
At first for about a year it would flutter exactly at 1200 rpm. Replaced throttle position
sensor, not successful.
Now it does it at random rpm after warm up.
Is engine light on?
Have you checked the coil packs?
I wish it had a check eng. light and have hooked up a scanner any way but no codes at all. The 5.4 has a coil for each individual plug / no coil pack. I also discovered it has no ignition module. Replaced cam sensor. Next step is crank. If that doesn't do it I'm gonna replace the fuel filter that my wife first suggested since we had a similar issue back 8 years ago and the fuel filter which is regulerly changed now was clogged. Will keep youall posted. Thanks
Sorry, I called them a coil pack but, yes, they are individual coils. I would think if you had a bad fuel filter, after over a year, it would be so clogged nothing would pass through. I still think it is ignition.
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