My truck has a leveling kit, and edge evo, magnaflow exhaust and a roush cai. It has the 5.4l v8 and is a 4x4. I have moto metal rims with nitto terra grappler tires. here is the problem:

i will be driving down the road and the truck will start to vibrate. it will not stop until you let off of the gas pedal. I have taken it to the ford dealership several times and "they can not duplicate the problem". does anyone know what is the cause of this?

 

Harmonic balancer loose or coming apart? I had the same problem on my '68 Camaro and I mainly felt the vibration in the gas pedal. Does it get worse the more you speed up, especially when you accelerate and even worse at a certain RPM?

 

Ya around 2k rpm and it doesn't stop until you let off of the gas