well, if you feel it wasn't well maintained, or if there's the slightest question about fluids and 'upkeep' items, start with that.
also, the AWD system can be very picky about tires. they must be the same circumference - that usually means all the same model and WEAR level. any issue with tires can cause jerkiness with the car - particularly tight turns on dry pavement.
Other sources of roughness/vibration can be in the driveline - shafts,u-joints,axles,etc.
paying a soob-experienced mechanic for an inspection might help you decide what needs immediate attention, what can wait, what you may be able to do yourself, etc.
if you post your city, someone may be able to suggest a shop.