This is a '97 5.4 with 115,000miles. I have a big loss of power and the engine shudders during acceleration, like its not running on all 8cyl. Truck idles fine, but as soon as you put it in gear it begins to miss, the more throttle the worse it gets. Started all the sudden. No engine light. I'm not sure what to look for on these trucks mainly because i've never had a problem with it. Any ideas greatly appreciated. Thanks in advance.

pat

 

Guess i'll bite it and let Ford check it out.

 

Did you find out what it was? My 98' 4.6 is doing the same thing.

 

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My dad's 99 5.4 f150 had the same problem, although it ran rough when idling and under acceleration but would somewhat smooth out when at 1500 to 2500 rpm. We took it to a shop and it turns out ford designed the coolant hose to go over the spark plug wire for the number 4 cylinder, and the coolant hose had a pin hole leak from being worn, and shorted out the coil for the number 4 cylinder, causing it not to fire. So this could be what is wrong with your truck.

 

I would suspect it has an ignition coil that's not firing a plug. However that would normally trigger the check engine light. Any shop with a scanner should be able to identify that pretty quick

 

Sounds like the coil pack on one of your cylinders. Mine did the same thing last week and I got it fixxed for about $140. But yesturday another one went bad so it's gonna get fixxed again tommarow. What happened to mine was too much offroading. The coil packs got hot and when i hit the water everything in the engine compartment got soaked and the water destroyed the coil packs.

 

Same problem here, I'm taking it into the mechanics soon.