I have a 2010 6.4L F250 with a DPF delete and Custom tunes from Eric at ID. Post tunes and delete I Got 16 mpg city hand calc. Put on an S&B CAI and my milage dropped to 13mpg. No one at ID seems to have an answer why. The MAF is clean and facing the right direction. I also unhooked the batteries while installing per instructions. Anyone had this problem and what did you do? Really frustrating.