Thanks for advising that, i just found a shock absorber was totally loose, i will get the car up and inspect everything,
I think i would have to analyze my geometry, i will measure my lift, tires, control arms and arms brackets. maybe i will find something out of place... in theory i have a 8" lift plus 38.1 Tires
The arms are designed to yield correct caster for a 6" lift on a 1991-97 Land Cruiser / LX450. and 2" drop brackets... i will measure everything again to be sure, and see what i got because i don't know why but i feel my geometry is not adequate.