Hello and welcome to JustAnswer!
It's not at all unlikely that the intake plenum needs to be replaced to repair this fault code. This code is for the performance of the short runner valve actuator. It can be the actuator, software, or a binding short runner valve.
The first thing that needs to be done, and probably already has, is make sure the powertrain control module software is up to date. If the car was built before a certain date then there was some revised software regarding this code setting.
The short runner valve actuator would then be removed and the valve moved by hand to see if it moved freely or not. If it didn't move freely then the plenum would need to be replaced, if it did move freely then the actuator would need to be replaced.
With your VIN number I could give you an accurate list price on the plenum for your car. There are a few different part numbers and the VIN would be needed to get you the correct number and price. It's not something you'll find aftermarket, the replacement will have to be from a Chrysler dealer or used from a junkyard.
Whether or not you can do the repair yourself depends on what you have for tools and your mechanical ability and experience. If you've removed intake manifolds in the past and normally do some intermediate level repairs then you should be able to replace it without much trouble. It calls for 1.6 hours of labor to replace it, so you should be able to have it done in roughly two hours.