mind of its own

I have a 97 delta88 with 105,000 miles on it, Sometimes while idling it will just start to rev up and down on its own, Any ideas on how to fix this problem, And what is the problem that will cause this to happen? Also does anyone have any ideas on how to stop the rub on this car with 20 inch rims already have spring spacers on it.

This might not be the problem, but take to EGR valve off and plug the hole that goes to the intake. If it doesn't do it then, thats gotta be your problem.