My truck is running rough.
Having a rough running vehicle is never a pleasant experience. Unfortunately there can be quite a few reasons as to why your GMC is running rough for you. With the limited information, and not being in front of the car, it is difficult to assist in pointing you in the right direction. It may be time to enlist the assistance of a certified mechanic to stop by and go over your vehicle with you. They will be able to inspect the vehicle from bumper to bumper and not only determine why your engine is running rough, but assist you any necessary repairs to getting it running smooth again.