I'm helping a friend with a 97 firebird (Formula) with a supercharged LT1 with a terrible off idle stumble that most of the time causes the car to shut -off. The bigger problem diagnosing this thing is that the computer won't flash a service soon eng lite even if you unplug sensors, when the Snap-On scanner is installed ocasionally you'd get a coolant temp sensor code which has been replaced but if any other sensor (Map, Maf) is disconnected it won't flash the code although the service engine light is functional when you first start the car. We tried a new computer and we had the same problem. The TPS MAF,and MAP sensors all check out good. The ignition 8x resolution check with my Vantage check out a little lower than spec so I'm thinking maybe the distributor might be the cause? Any similiar bad distributor symptoms out there? Any suggestions?