I have a 1995 Z71 4x4 with a 350 motor. It has about 162,000 miles on it. I have already done a full tune up on the truck. I have also tried code retrieval. Only code 12 kept flashing. Nothing else. When I drive the truck it will start sputtering and is not responsive and sometimes goes dead. After going dead, it will crank right back up. As long as it is sitting and idling it is fine. It only has problems when driving. Any help with my problem would be greatly appreciated.

Thanks,
Dwayne