So I was driving my Z06 putting miles on it to break in the new diff and lube when I all of a sudden had a stumble and rough idle sitting at a light, then my SES light starts to flash! It flashes for maybe 20 sec. then goes away. Car runs a bit rough but within a handful of seconds all is normal again. So about an hour later( been driving fine up to this point) it starts again, this time the car is running really rough now. Coming off a light in 1st gear the car will barely accelerate,just breaking up terribly. have to give it a lot of gas to get it to move, when I get into 2nd not much better, 3rd is ok, but Im on the gas pretty heavy to get it to rev and mov!! Coming to a stop I throw it into neutral and the rpm drops down to 3-4 hundred rpm and I have to rev it so the car wont stall. This time though I dont throw any SES light. I limp the car into my garage and thats it. I put in new plugs and wires 7 weeks ago, so all is good there. Pulled off the valve covers no sign of broken valvespring. Im wondering could it be a coil pack? When I look into the black brass connector where the plug wires click into. The small pin head sized tip is shiny clean brass on 7 coils but on one if them the pin head is black. Could this be the coil is malfunctioning perhaps, although all the plugs looked good, but I only drove a couple miles at the end with it running bad.

 

I had MSD's that threw this code went back to the stock AC Delco's. Fixed the problem all together

 

If you have a dead miss and it is consistent, isolate the miss to a particular cylinder by unplugging the coils or removing the plug wire with a wire remover. Have a friend keep the RPM's up if needed. When you hit the missing cylinder, the idle or quality of the car's running wont change.

Once you have the cylinder isolated, switch a coil with another one and see if the miss moves to that cylinder. If it doesn't, start looking at the plug, wire, injector, and finally compression and valve train.

 

thanks. Found out its a flickering O2.