RE: 96 Eclipse RS

im looking to purchase this eclipse and i was told it has all new rotors, in the front and back, new tires, new engine mount.  However, when stopping it shakes really bad and the idle messes up when slowing down/stopping?  Any idea of what it could be? timing belt? suspension? 

Likely to be trans. or suspension.

is it automatic or manual?
 
And what does the idle do exactly. Does it drop like it wants to stall out?

Its an automatic with 170k

My car did the same thing, get your tires alignment checked that seemed to clear things up for me not sure about the idling factor though