1998 Chevrolet Silverado 5.7L - P0300 Multiple Cylinder Misfire at High Speeds
Hi everyone, I'm having an issue with my 1998 Chevrolet Silverado equipped with the 5.7L V8 engine, which has accumulated 122,000 miles. The vehicle is throwing a P0300 code indicating a multiple cylinder misfire. This problem only occurs when I accelerate aggressively at higher speeds. I'm wondering if this could be related to my distributor or ignition module, or perhaps another underlying issue. Additionally, I've noticed a small RPM surge around 40-45 mph—could this symptom be connected to the misfire? Any insights or troubleshooting tips would be greatly appreciated!
I recommend checking fuel pressure using a fuel pressure gauge during a road test, with the gauge taped to the windshield for visibility. Low fuel pressure is likely the culprit—alternatively, vacuum leaks, damaged spark plug wires, faulty distributor cap, weak ignition coils, or a clogged exhaust converter could also be contributing factors.