About a month ago had a check engine light come on and had to take it in. The PCM was replaced and truck reflashed. Since then my mpg has dropped from 17 to 14. Alsoit seems i get better mpg when i do not use any additive. anyone have any ideas???? I have been towing a 6x12 trailer with the Harley on it. Today i made a 450 trip with 2 bikes and it avg 14mpg. I drive the speed limit since it use to save fuel. Anyone have any ideas???