Have 2002, F-150, 4.6 triton. Ran great, parked on Friday, started on Sunday morning had very bad miss. Check engine light came on, (Was very cold that weekend) Took to garage, they showed a miss on #8, installed new spark plugs, cleaned injectors, checked fuel pump pressure, and replaced #8 ignition coil. Ran good until the next morning, and now miss is back. **As engine warms up, miss is not so bad, but still there, only under load or aceleration. If I stop for 15 minutes and then come back and run the truck, THE MISS IS GONE! But if the motor cools down, the miss will come back until it warms up. Took it back to the garage and the computer reads everything is normal. But it will still miss upon startup until it warms up and is shut off for a peroid of time. Does this sound like a "choke" problem? P. S. under slow aceleration on warm motor there is no miss.

 

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I was having a very similar problem with my 2001 F250 5.4 and a friend suggested putting a fuel system antifreeze and cleaner in the fuel. The problem cleared up with in 5 miles of driving. I am also going to change the fuel filter tomorrow.
I hope this helps you, Pete
I used Prestone Cold Start

 

Done thia also, but will do again. Have used a gallon of injector cleaner and deicer. Worth another try though. Thanks, J. Smith

 

My best suggestion would be to run it by a Ford dealer and let them test it with their scan tool. It will give realtime data that may show what is going on. It will probably cost about an hours labor, but it is better than throwing parts at it.

 

I know, but you know how this man-thing is. I have come to the same conclusion, I need help above and beyond myself. Thanks, J. Smith