My 2003 monte carlo 6 cylinder, is idling at 2k rpms when in park, other problems in post.?

While I'm in park the car idles at 2k rpms. Also when I start driving if I take my foot off the gas pedal it keeps going at the same speed I was going before as if my foot is still on the pedal. When I get into shifting into 2nd sometimes but mostly 3rd gear the car's rpms will start to flutter and it wont shift.