I've got a 97 Expy 5.4L 4x4 with 66K miles. Yesterday it started pinging on my way to work. After it warms up the pinging goes away. Its not cold in the morning and I filled up about 4 days prior. Its now at about 1/2 tank and still making the noise. I buy my gas from Cosko. Any thoughts.


I'm leaning to bad gas but unsure still.


Thanks


Big MIck


PS. I did a search of this forum and didn't really find much.