Whenever I'm on the gas at all- even just enough to maintain a constant speed above about 45MPH the whole car feels like it's about to come apart. My first thought is a CV. My mech. agrees. The thing that's starting to make me doubt is that if I floor it, the car goes dead smooth. Going up a hill, or giving just enough throttle to build boost but stay in 4th gear makes it hard to even see straight, but stomp on it and it's like gliding on ice. It doesn't feel like a mis-fire at all. It's just this deep rythmic vibration through out the entire car. Nothing shows up on the scanner to indicate it's in the engine. Also the CV boots are perfect. Am I thinking about it too hard and it's really a CV or could there be something else? It did it real slightly when I bought the car. Felt like an out of balance tire, but now I don't even want to drive above 40mph it's gotten so bad.