Few things I would check with the overheating would be coolant lvls/condition. Check for air in the system and if all that looks ok replace the thermostat. Check for vacuum leaks, plugs and wires for the rough idle. In my 93 I had a horrible Idle and it turned out to be a vacum line that I had knocked loose while servicing. But if this is a new purchase deffinatly check your plugs and wires.