I have a 2006 quad cab 6 speed, The first few days I was getting 17-19mpg city and 18. 5 @ 65 hwy. Now I am getting 12. 7 and dropping intown. All kinds of power and plenty of soot on fender. Now since the rains have started it misses in the morning for first 5 to 10 minutes. With 20k miles on...