If it's been sitting that long, the first thing I would do is change ALL the fluids (ok, not the wiper fluid). Oil, brake fluid, steering, transmission, differential. How much gas is in it? It will need fresh gas - what is in there is probably not helping your idle issues.
Next would be the rubber - particularly fuel and brake lines and the tires. Check for dry rot. If you rub the rubber and your hand comes away black, replace it.
Buy the Bentley manual for the car and start doing all the 'routine maintenance' stuff - new spark plugs, new filters, etc.
Congrats on the purchase!