The Ford Mustang GT, with the optional 5.0L/302ci V8, may develop misfires, rough running, and loss of power, accompanied by the check engine light illuminating. Ignition wires can rest on the exhaust manifolds if they are not properly secured. The hot manifolds will melt the insulation on the wires, damaging the wires and causing the mentioned condition. Replacement of the ignition wires, and securing them away from the exhaust manifold is necessary to remedy the rough running conditions.