I have a 2000 with the 5.4. We took a 600 mile trip, 300 miles each way. Going up hills the engine seemed to miss and stutter, on the way home it threw 2 codes, lean mixture and misfire. I just picked up the SUV 6 months ago and with 134K on it I was sure it had the original spark plugs. So off to the shop I go.

Turns out someone put in Bosch plugs and they mechanic told me they were garbage, so he replaced them with the OEM Motorcraft platinums, but here is the
main culprit. He checked the fuel filter and he said it was like 90% clogged. He said he couldn't blow through it. So new fuel filter and the truck has been fine since. I keep forgetting sometimes a fuel issue will act like it is ignition.

 

huh? what are you trying to say

 

Hi - I can't resist - I think he's trying to say - wish I had done the fuel filter first as while the plugs got changed, maybe they wern't that bad. Also when I had some issue with my 4.6 it was in fact the plugs, but no codes, a much more minor miss under load. So I did the plugs and the cops and that made a huge difference.

Anyway, always interesting what we learn from each other.

Mike

 

He's just telling his story, hoping that someone else will first check the fuel filter and save themselves a few bucks.