98 Z71

Ok I got this 98 Z71 that at 45 Mph or faster will studder intermittently. anyone out there every have this and how do I stop it?

Ive Got A 94 Silverado That Does That...one Of The Guys Here Said The Torque Converter Is Going Out.....he Also Said The Next Time It Happens Tap On The Brakes.....it Hasn't Done The Shudder Thing Since Then... Its Bout A Month And A Half And Haven't Feel't It Yet.