I was driving home today on the freeway and my impala was stumbling today and i am not sure why. I have no MIL on and i was looking through it on my snap on brick and it said EST grounded any idea. I looked through my book today and it said wiring issue i wonder if anything is touching my headers it has started apparently after so. I will look under the car and inspect the wiring underneath perhaps a knock sensor wire is loose. Hit me up with any info please.