There is a thumbing sound and the vehicle shudders badly, and there is a loss of power. The more I accelerate the louder the noise is. At first I thought it was a warm up problem, but after a fifteen minute warm up the problem still there. I took it to a certified dealer and I explained my problem to the service rep. I asked them to drive to vehicle to duplicate the problem. When I returned I was told that a computer update and that this problem should stop after driven a few miles. I don't think my vehicle ever lift the shop for a road test.

What may be my vehicle problem and how should I handle this situation?