1998 Oldsmobile Cutlass car surges

1998 Oldsmobile Cutlass mileage: 104,000. My car will buck and surge at various speeds. Stalls every time you come to a stop at a light. I took it to the shop and they put it on their computer, there were no readings of anything wrong. The mechanic then drove the car, came back and said it seems to be shutting off for a second and coming back on. His diagnosis was an ignition problem. Changed the ignition module and coil pack. We did this a month ago. Car would still buck and surge but stopped stalling. The car will drive fine sometimes and other times it will buck and surge. Now when you drive it the indicator lights on the dash flash, the speedometer goes crazy and sometimes the whole dashboard will go blank (digital dash). They seem to think it's electrical but don't know where to go to start looking. They did talk to a GM tech that told them there is a secondary wire going to the computer that sometimes shorts out. Well they cut open the wire harness going to the computer under the car and found no bad wires. If you guys have any ideas I would greatly appreciate any input.