I had a local (and reputable) shop put a Zone 3" lift on my '09 Wrangler X 2 door. I've noticed that, on highway driving on changing surfaces as I approach or surpass 60 mph, the vehicle begins to shake quite a bit...seeming to be most noticed at the rear of the vehicle and then spreading forward. If I let up on the gas, or apply the brakes, the problem disappears...but this isn't always advisable while highway driving. Any suggestions? I am planning on a front end alignment AFTER I put on new, larger wheels and tires, but I'm uncertain as to whether this is the root of the problem.