I think all the suggestions thus far are great. Definately change all the filters and fluids (if they're due). Plugs, wires, belts, too.
Do one thing at a time, run the car, make sure everything's a-ok, then do the next thing. This will help troubleshooting in case you have trouble.
If you're cleaning the manifolds, etc., you might consider optimizing the TB while you're in there. Cheap to buy, too, if you don't want to DIY.
