Do yourself a favor before you replace anything. Try cleaning the carbon off of the butterfly plate as best you can.
removing to clean is your best route. be shure to remove any sensors (throttle position sensor if it has one, make sure the screw marks line up when you put back) carb cleaners usually screw them up, also take off clean carbon/sludge, and put back IAC valve.
This is easier than you think, only takes 10-20 minutes total.
parts needed; 1 can of gunk, paper towels, new gasket.

This should cure your problem I practically warranty it, Thank you come again.