I have a 2003 Ford Windstar witht the 3.8 V6 giving me a P0305 (Misfire on 5). I have replaced the Coil, Wires, and Plugs. The engine still misses. A diagnostic found no compression problems. Before I replaced the coil, it was sending P0303 (Misfire on 3) After the coil was replaced, the code cleared and the engine ran well for about 300 miles. It started misfiring again and now is giving the P0305. I don't know how to diagnose what to try next. Reading online makes me wonder about injectors and oxegen sensors. I don't know how to diagnose what to replace next.