What should you do if your right wheels drift off the roadway and drop down several inches to the shoulder?

First off, do not panic which is why most people oversteer and wreck when this happens. When this happens you lift your foot off the accelerator, firmly grasp the steering wheel with both hands, and slowly steer back on the road. Do not steer sharply, jerk the steering wheel, or slam on the brakes. If you do you will more than likely have an accident which can be fatal. It is just a matter of slowly moving back to the left and on the road. This is something you really need to practice a few times so that if it happens you will know how to handle this situation. Practice this at a very low speed until you get comfortable doing it, then you can speed up some. If you do not panic you will be fine and nothing bad will happen.