An ignition coil may fail causing one of the cylinders to misfire. Each of the two banks of cylinders has its own coil assembly. If one ignition coil fails the coil assembly for the corresponding cylinder bank must be replaced.Google+
Car Problem Reports
Cadillac Eldorado Misfire Due to Failed Ignition Coil
Cadillac Eldorado Problem
Average Mileage: 69,250 mi (65,000 mi - 73,500 mi)
Visitor, 2000 Cadillac Eldorado, 65,000 mi
Had to replace rear coil pack after getting PCM0300 misfire code and going into limp mode. Got part used w/ 1 year warranty for half cost of dealership. Replaced myself, took the opportunity to replace plugs & boots as well. Took about 45 mins including all plugs and boots for both sides.
Intermittent misfire caused by coil for cylinders 2 and 6 repaired this prolem.