I have a 2004 5.4 3v with 69000 miles that runs ruff at idle only. I have taken it to the dealer and was told that 1, 3, and 7 show weak spark. then advised to get new plugs. The question is could it be the coil packs and not the plugs or both.Also I have what seems like a slight slip when taking off only at start up and leaving my driveway. Any advise or sim. problems on this would greatly help me out

 

Welcome to FTE. Well spark plugs are cheaper than the COPs... so I would start there with a fresh set all around (if they have not been done recently). Are you talking about a drivetrain slip?

 

Thats the thing its like a rear end slip but hard to tell " kinda like wet pavement ". It only does it one time when i first start up and leave my house after that its fine

 

x2 on the plugs, and on the slip. do you feel a small vibration with taking off? almost like hitting rumble strips or is it just a slip

 

there is a slight vib long enough to feel then its like the tires caught dry pavement

 

yup i had the same issue, just had ford do a tsb that was for the limited slip in the rear end
Heres the post the vibration doesn't last long at all but long enough to know something it different.
https://www.ford-trucks.com/forums/8...vibration.html

 

I'd check the fluid level in the transmission and make sure I'm not low on fluid. Have you ever changed the transmission fluid and filter? At 69k, you're past due for one. You might also want to check for codes.

 

i have checked the level and it look fine I got this truck used so i have no ideal about if and when the filter was changed