Try a K&N cold air intake. Here is an example.
http://www.autopartswarehouse.com/pe...d=43&year=1999
Now if you look around on eBay and some other sites you can find, non-name brand cold air intakes that still have the K&N air filter on the end, just a much cheaper tubing. A friend of mine bought an off-brand one with a K&N filter at the end for his 1996 Grand Prix for under $100 and he loves it. Look into some lower restriction exhaust but make sure they will pass MO state regulations.
Things NOT to buy. Microchips, they don't work like they claim they do. Tornadoes or anyother of those stupid spinners, they only make things worse.