Warner1985

As stated in title my 1997 k1500 4x4 with 5.7 engine has a shimmy/shudder when gently giving accelerator pressure starting at around 45 mph. Pressing more firmly on pedal and I dont notice it. Letting off gas and then easing back on it crests a more pronounced shudder. I first noticed it a while back when starting up hills on the highway when adding pedal pressure and now it it more frequent.
any thoughts?