I have a 06 fx4 with 5.4 3 valve thats throwing code 0351-0358 missing on every cylinder. I have changed all 8 plugs with Motorcraft SP-515. And all 8 cop's with Motorcraft DG-511. No vacuum leaks to be found. catalytic converter have been removed. Fuel pressure seems adequate. Has rough idle and no power . Seems to clean up a bit under hard acceleration but motor lug bad maintaining any speed (15mph or 80mph) with or without OD on.. any ideas would be great.
My car has 145000 miles.
My car has an automatic transmission.
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