Toyota Repair: 1996 toyota doulble cab, steering, tank slapper, steering damper

Question
Two questions,
1.when going round tight corners or pulling out of juctions the steering is not centring it self,the tires are in good condition and it has been tracked and blanced,the steering box has no free play and all steering parts seem in good condition.
2.when drivig at around 50 mph if i hit a change in road suface or a small pot hole the whole truck shakes,I can liken this to a tank slapper on a motorbike,you can not accelerate though it and have to come off the gas to get control back,I have fitted  a new front prop shaft recently  and a new heavy duty steering damper,could this be the birfeild joints and/or half shafts and is this linked to the first question?

Answer
The second part of your question does seem to be related to the first problem, there is something in the suspension that is out of alignment, the shaking of the front wheels could be caused by an exessive negative caster condition, it sounds to me that there may be some suspension parts that are bent or possibly a bent frame, the fact that the steering doesn't self center tells me that there is something very wrong with this vehicles alignment, have you had the alignment checked on a good computerized machine?