P0302 Misfire Diagnosis and Fix for 2002 Ford Ranger - 6-Cylinder 3.0L Engine

HELP! My 2002 Ford Ranger with 140,000 miles has been experiencing severe engine bucking for three weeks despite extensive repairs. I've replaced all major components including spark plugs, wires, fuel pump, air filter, lifters, valves, injectors, sensors, and the coil pack. Compression tests show normal readings, and the catalytic converter is functioning properly. However, the vehicle still bucks significantly—especially on hills—and the OBD2 fault code P0302 (Cylinder #2 misfire) persists. This truck has been well-maintained, and I deeply love it—it's a classic Tremor. The issue appears to be mechanical rather than electrical or fuel-related. After further investigation, I discovered that my vehicle was manufactured in California, not Pennsylvania, meaning it is subject to California emissions standards. The root cause turned out to be a severely misaligned Y-pipe with five catalytic converters inside—this caused significant backpressure and uneven engine performance. My second mechanic removed the main catalytic converter and tested the engine without it. The vehicle ran smoothly, confirming that the Y-pipe had major clocking. Replacing this component cost $1,300 (shipped from California), as such parts are not available in Pennsylvania. After replacement, the check engine light turned off—P0302 is now resolved. Key takeaway: Always verify your vehicle's emissions origin (California vs. Federal) by checking the engine bay sticker. A faulty Y-pipe can cause persistent misfires and should be inspected if other components have been ruled out. This was a costly but critical issue—total repair cost reached nearly $4,500. I strongly recommend that anyone experiencing P0302 on a 2002 Ford Ranger check their Y-pipe and emissions compliance label before replacing parts blindly.