Best of luck! First thing to do if you get is look at the rear brake callipers ensure theyre not sticking or seized, have a look at the condition of the exhaust as these tend to perish with age and get any recalls done if any, lucky if you do have an outstanding recall Lexus will do a complimentary health check so could give you an indication of anything that may need doing. Generally as long as you service your IS250 every year itll look after you and last forever,