My navigator surges, has flashing engine light, reduced power, smell of fuel coming from tailpipe, along with unburned fuel and severely reduced fuel economy.

Do not drive it with the check engine light flashing as this may damage the catalytic converters. A flashing check engine light indicates miss-firing and when this occurs raw fuel is dumped into the exhaust system and ignited in the catalytic converter. The burning of the excess fuel in the catalytic converter will cause the converter to overheat either melting, burning or cracking the substrate material that is inside. Catalytic converters are expensive to replace. You need to get this vehicle to a mechanic right away for proper diagnosis and repair.