An engine miss involving two 'dead' cylinders, one on each side, may be caused by a push rod hole in the cylinder head breaking through into an intake port. If this condition exists, remove the intake manifold and examine the intake passage in each cylinder head. If the push rod hole in the cylinder head has broken through into the intake passage, cylinder head replacement will be necessary.
General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.