Something funny about screwing up the oring in the fuel line quick connect?

 

yeah with less spark plugs mileage goes down, just went through this with a truck running 7 spark plugs and a loose one

yeah mpg low is a tell tail sign, and if its been that way a long time might back fire with new plug and have to dump seafoam in

 

Kail,
I did not really notice anything at the time, but does seem to be a little quieter now.

Speedy

 

I guess I'd better check the plugs in my new 2019 Ford F250 Superduty 6.7 Diesel
Sam