Pontiac engine revving in park

I have a 2000 Pontiac Grand Prix. 3.8 V6 supercharged if the matters. But when the car is idiling in park, the engine will rev on its own. I know its not supposed to do that. I checked the vacuum line, I think thats what it is called, and there was a hole in it. I spliced it and fixed the hole but it still continues to rev up the engine in park? Any ideas why this would happen? Thanks