My car shimmys and vibrates somewhat sideways on acceleration between 45-50 mph. The vibration can be felt on gas pedal and steering wheel. Once I exceed this speed the vibration will subside as it is when traveling below 45mph. The check engine light did come on prior to this vibration. It was diagnosed as a faulty mass air flow sensor. Before I was going to purchase this 300 dollar part I told mechanic to look for something mechanical first. He checked tires for any ply separations, noticed some run-out on tires so re-balanced them and checked the front end to be very solid. He did get me to replace a front wheel bearing on right front and also put in a new drivers side motor mount. I still have this problem. Could this be mass air flow sensor problem?