I believe that's refered to as an "Italian tuneup", running the car for an extended period of time, on the highway, at max speed and rpm. The logic is that your raising the internal engine temp past what it normally sees and this, coupled with the high flow of intake charge and exhaust, is supposed to help dislodge carbon buildup and other engine deposits and make the car run smoother. Seems a little scary to me.

Sorry I couldn't help you with your problem.