I have a 1992 Honda Accord 80,000 miles. When I start the car first thing for the day, and start, when the rpm gets to around 3000 the gauge jumps all over. It goes up into the red and back down. The engine does not seem to be over reving or hesitating. After about 20 minutes running all returns to normal for the rest of the day. I have had the main relay and igniter replaced by the dealer. No change. Any ideas??