my 03 f150 shakes on the highway and at low speeds you can hear a clunk from the front end and when i come to a slow stop my abs comes on. i have no idea whats going on with my truck. any help would be awesome.

 

check your front suspension components and steering components...tie rods and connections etc..if available lift your front in the air and give your front tires a good shake to see if the ball joints are done for...if it wiggles you need new ball joints...

Did the the abs light ever come on before this problem? Is your rig 4x2 or 4x4?

And is it a body shake or a steering wheel shake?

Judging by the clunk clunk sound your hearing at low speed sounds like wheel bearing...which would vibrate the crap out of the abs input sensor...