found out it was my number 4 spark plug misfiring. finally running good. thanks for all the help and advice guys.

 

Thanks for posting a follow-up to let us know how you solved your problem!

Stewart

 

i found out that most people dont do that. but yeah its runnin great! thanks

 

I had a similar issues with mine as well and i had to learn the hard way. You must use OEM plugs in these trucks. they are peculiar as hell. While you are doing this, go ahead and check your primary and secondary OHM resistance for each coil. You can do this with most multimeters in your garage and it will take only 30 min or so. if a coil is .2 of an ohm off, that coil may be your culprit. Primary ohm- .55 secondary is 5.5kohms. (these numbers are for my 2005 5.4l) if your engine is the 4.6 or other, you can simply look up the resitance parameters for your model.

 

other than 1000 to 1500 rpm's and at idle the truck (2004 ,5.4 , fx4) runs good but that is the main operating area ? don't know what is wrong, having the FORD dealership hook it up in the morning! any ideas?

 

when it shudders try to make the engine light come on. thats what i did. i kept the throttle in the shudder area. found out it was #4 and #8 spark plugs.