Check you throttle position sensor , sounds like it's bad ? If you don't know where to look , it's at the throttle body on engine where the cable from your gas peddle hooks up . Go to autozone ( or parts store of your choice ) and I'm sure they will show you where it is located . Does it have any " check engine " lights showing on your dash cluster ? They will do a free scan of your car to see if any codes are showing and can advise you to the parts you may need . Good luck and let us know what you find out !