1998 4.2 180k miles. around every two days or so I get flashing check engine light and code P0303. truck runs great. I get no misfire, hesitation etc when light comes on. No performance disruption at all. Light flashes for 20 seconds then stops. Plugs, wire and wire block are about a year old. Plugs were clean when I replaced them about a year ago. I am thinking maybe fuel injector glitches? Any idea?

 

What do you mean "no misfire" when you have a misfire code? Does that truck have a misfire counter?

 

No misfire. Not a single thing. Truck runs smoothly. When check engine light comes on no interruption at all. I would expect even for just a second some kind of shudder, misfire, vibration or something from engine but nothing. That is what puzzles me. i would never even know there is an issue if didnt see check engine.

 

My old neighbor had a truck with that engine and there was a loose plug. Were the ignition parts Ford?