Not sure if you guys can help I'm havkng trouble with my 03 f150 5.4 l it's throwing a cylinder 1 misfire and I've already replaced spark plug and cop. You guys think it may be fuel injector. It only misfires for maybe a mile then straightens itself out after that until the next startup

 

Put a can of Gumout for high mileage engines in a half tank of gas and run it through.

 

Chevron/Techron can help the injector's also. I used it in my 5.4 that was in my '04 Lariat and that engine ran great.

 

Mason, welcome to the forum.

Please don't start multiple threads on the same subject. It leads to confusion and wastes everyone's time, including yours.

I moved the thread you started that had replies to the V8 forum, where I think you'll have the best chance of a helpful response.

- Jack