2002 Chevy Silverado stutter

My 2002 Silverado will have a slight "stutter" while driving down the highway, between 50-70 mph. I feels as if the power to the drive train just quits for a half second and then resumes again. This doesnt happen evertime that I drive, but seems to have become more frequent. I have changed air filter, spark plugs, oil, checked gear oil and clutch fluid.