I've got a 5.4 '98 F-150 with about 123,000 miles on 'er. I recently noticed that I'm only getting about 13 MPG. On my last oil change, I replaced all the spark plugs and I also noticed that my fuel injectors were pretty dirty. I was thinking about replacing all of them, which is going to be pricey. I'm wondering if I would benefit from spending the 300 or 400 bucks on new injectors and increase my fuel economy. Will changing them make that much of a difference?

 

I bought reconditioned ones off e-bay for about $125 a set a couple of years ago.. I would run techron through it and see if that cleans them up. My 97 E350 had its original injectors when I sold it last month and they still worked great with 235 thousand. Didn't see any difference when I replaced mine. Run a bunch of techron. That will clean them and they likely be good for another 125k..

 

I don't think replacing your fuel injectors will really improve your fuel economy. With 123K on the clock, are you still running original catalytic converters? How about O2 sensors?