Problem solved! Thanks you for all the replies and advice. There was 2 problems: The first was the front centre spark plug. It had a hair line crack running in the long axis of the plug. I am not sure if it was my bad or damaged when I bought it. That plug was one of the easier ones to do though. The second problem was my bad. The spark plug on the rear bank on the driver side, just above the manifold was hard to find the hole. In my attempt to fish for the hole I collected some dirt and greasiness in the gap. Well, I returned the bosch plugs and got the AC Delco plugs. (Autolites was not available around here) The car runs great now. I live in Edmonton Alberta and my car runs 145 Km every day in winter, snow, -40, +30 in the summer, best car I've ever owned and plan to replace it with another Grand Prix when the time comes. I first want to see this car break 300 000 km. This forum is awesome! All I can say now is that lessons are has been learned and I am great full you guys are able and willing to help. Thanks again!
