Welcome to FTE. We've seen almost every problem you can imagine, but in order to help you, we'll need more specific information. Can you give a better description of the sputtering and rough idle? Does it have issues through all rpm ranges? Does it feel like it's not firing on all cylinders? Does it only act up in the rain, or does it do it all the time now?

And of course, what motor do you have in the truck? Diesel vs. gas motors have different parts that might cause this.