If the fuel pump looses power and the car bucks, a bad connection at the fuse, A defective RPM relay, or the Inertia switch could be breaking ground or loosing connection. But, If the pump is running and your able to drive the car, then the power loss is more than likley in the tune up or in the fuel distribution. A very common problem is the warm up regulator, they are getting 20years old. When was the last tune up. John hervey www.specialtauto.com these symptoms?