i have a 98 1500 and when i put it in gear it idles up to about 1500 and stays there when you push the throtle its like it is stuck to a minute then it catches back up.

 

take your iac off and clean the pintle and the hole on the throttle body that it blocks off with carb cleaner then dry and reinstall. don't twist/push/pull or try to bend the pintle, if you do then it'll break. if that doesn't do it then grab a haynes manual and run through the tests for the iac.