97 Pontiac Bonneville, 3.8L V6, 130,000mi. While driving to work, it began to run roughly and the MIL was flashing. I turned around and was able to make it the 7 miles home. Later in the day I started it up and it idled and ran rough no matter what the rpm. The MIL was on constantly. After shutting it off, it will no longer start. When I put the code reader on it the fault code that came back was P0300, Random/Multiple Cylinder Misfire Detected. Any advice on what to check and/or replace to fix this problem would be greatly appreciated. Thank you for your assistance.