Worth a check of your front wheel spindle pinch bolts.

XT's can do this if the are under or over tightened...

http://i227.photobucket.com/albums/d...SNC00022-1.jpg

i did notice a difference when the bike is doing a long stunt..like 30 mile on the m way.. it can be worse,, but when the bikes just about the streets,, its not so bad... Funny eh ???

I don´t think we´ll be able to help much more unless you tell us you have checked the front wheel bearings, the head bearing, the front wheel alignment, the front tire, the spokes, did a full inspection on the fork (check guides, seals etc., checked the front spring for correct length and assembly, change oil) and balance. These are the basics.
Cheers
Chris

ok Chris.. thanks