Exhaust System Backpressure
WARNING: This page does not describe the selected car, but rather 15 other vehicles, including the 2000 Mercury Villager, 2000 Mercury Mountaineer, 2000 Lincoln Navigator, 2000 Ford Windstar, and 2000 Ford Ranger. However, it is still accessible from the selected car via links, so may be relevant.
Using a vacuum or pressure gauge, check exhaust system. Remove Heated Oxygen Sensor (HO2S) or air injection check valve (if equipped). Connect a 0-5 psi pressure gauge, and run engine at 2500 RPM. If exhaust system backpressure is greater than 2 psi, exhaust system or catalytic converter is plugged.
If using a vacuum gauge, connect vacuum gauge hose to intake manifold vacuum port, and start engine. Observe vacuum gauge. Open throttle part way and hold steady. If vacuum gauge reading slowly drops after stabilizing, check exhaust system for restrictions.