RepairPal Certified shops can diagnose and repair your 2002 Cadillac DeVille. They provide transparent pricing with a minimum 12-month or 12,000-mile warranty on repairs and services.
i had the same issue but mine would misfire above 40mph. The dealer told me there are 2 coils - one in front and one in rear, 90% of the time it is the rear due to excess heat. I inquired about changing both but was told it was not needed.