My friend has a 2003 with the 5.4. Pickups all stock. It has a terrible shake. Hell be drivn down the road at 60 then itll start shaking then it stops shaking then a few mins later itll shake again. It dosent shake over 80 mph. He told me it was a u-joint???? What do you guys think?? Theres no clunk going in or out of gear.

 

Before anything else I'd make sure the tires are balanced. Start at the easiest solution.

I had a set of kumho muds on my ranger and they shook intermittently at higher speeds. For whatever reason they would go in and out of balance. A new set of all terrains fixed that.

 

I would place my bet on a COP that is misfiring. Get someone with a scanner that can data log and go out and look at the misfire counts.

 

It could be any of the things that the guys mentioned above. Whenever somebody says "Shake" I think of a shake in the steering wheel that happens at certain speeds and conditions on the road and will sometime start at one speed and stop when you go faster.
These type of condition are usually something gone bad with a ball joint. On a Ford truck, I would inspect the upper ball joint control arm. You will feel the shake I am talking about in the steering wheel. If so, check to see if the control arms on both wheel are loose in their attachments to the frame. You may also see a loose ball joint where it attached to the spindle of the wheel. If it is real loose, just jacking up the wheel and having someone try to move the wheel and tire while it is in the air will result in movement that should not be occurring. Be careful when moving the wheel that you don't move the wheel truck off the jack while someone is under the truck.

 

i had similar problem and it was warped rotors. Not say that is problem but its worth checking. I replaced my rotors and problem was gone.

Performancebrakes.com is where i got my rotors from. They look awesome too.

 

Setting the parking brake, etc are always good safety precautions.

 

Thanks guys im guna let him no and well see from there.