98 Dodge 1500 P0305 Code: Diagnosis and Solutions for Misfire at Low Speeds
I own a 1998 Dodge 1500 4x4 with over 170,000 miles. I drive approximately 71 miles one way to work, and while the vehicle runs smoothly on my return trip, it begins running roughly at lower speeds when driving on a two-lane road. The engine feels like it's struggling for fuel under light load. I recently replaced all spark plugs, but the P0305 diagnostic code persists. I've checked for disconnected vacuum lines and found none. What could be causing this misfire? Any troubleshooting steps or recommendations would be greatly appreciated.
The P0305 code indicates a misfire in cylinder 5. If you don't have an OBD2 scanner, it's important to inspect the spark plug condition—specifically how wet, dry, black, or tan it appeared when removed. A wet plug may suggest fuel delivery issues. Otherwise, consider checking fuel pressure and performing a leak-down test when the key is off. This can help identify a faulty injector or a failing fuel pressure regulator (FPR). Additionally, an exhaust restriction could be contributing—using a vacuum gauge would provide more insight, but without additional error codes, start with fuel pressure and leak-down testing.