Warning replace your Plugs don't believe GM

Well I fixed the stumpling at various speeds. I decided to start with the plugs and that was it. Problem fixed. Don't believe GM when they claim that the plugs will last 160,000km or 100,000 miles. Mine start going at 105,000km or 60,000 miles. I guess the gas in the Toronto area is bad. I have heard many experts claim that our Canadian gas is loaded with sulfur I now believe. Oh yaw it was a bear trying to remove the spark plug boots they were almost melted on the plugs and for 1 of the plugs I had to remove the oxgen sensor in order to remove the plug 3.8 engine