My 06 5.4 liter has developed a bad miss and really low mpg. I'm getting around 9.5. Mpg around town and maybe 11 on the road (with 35 inch tires). The check engine light came on and I stopped by Goodyear and they checked it. The code came back as a knock sensor. I bought the truck a year ago and it now has 75k miles on it. I've never tuned it up and I'm not sure when it was last tuned. I called the dealer and they quoted $700 bucks to replace the knock sensor. Realistically what should I expect to pay and is the knock sensor the real problem or could it be something else?

 

you shouldnt have to pay 700 bucks its real easy to change if you no what your doing

 

Spark plugs?