Just bought a 2001 supercrew with 48,000 miles. Twice now I have had a shimmy in the front end going about 55. At first I thought it was an imbalanced wheel, but it goes away after slowing down. I haven't been able to re-create it at will.
Anyone else experience this problem?, any suggestions as to where to start?

 

check your ball joints. They are probably ready for replacement.

 

You have quite a few things to check beside your ball joints. Search using "shimmy" , and you'll see what I mean. Incredible to see how many things have caused similar problems. Ball joints, tie rods, pitman arm, idler arm, steering box, steering shaft, U-joints, driveshaft problems, out-of-balance tires, out-of-round tires, flat out f-ed tires, bent rims, loose bearings, warped rotors, out-of-round drums and a partridge in a pear tree. Start with the most important (safety related) items, and work your down the list.
If it were me, I'd check, in order: ball joints, tie rods, P arm, I arm, bearings, PS box, steering shaft, warped rotors and/or drums, tire balance, road force check for out-of-round tires, bent rim(s), U-joints, driveshaft. Good luck with it.

SL