2001 6.8l v10
 

Been having some issues with rough running horrid fuel mileage and terrible power. Had a diag done and came up with cylinder 3 and 7 miss fire confirmed and cylinder 6 miss fire pending. Replaced coil packs on 3 and 7 and made no difference. Undid cyl 6 in an effort to save money on another coil pack and the engine ran worse. Today I picked up all brand new plugs and another coil pack. Any other thoughts on trying to troubleshoot this and correct the problem?

Sometimes Ford Computers don't always tell the truth. By that I mean , they will tell you cyl X when it is really cyl Y with the misfire. Coils have been a problem and depending on the mileage you may come out further ahead by replacing all the coils and boots at the same time. Have found from some bad experiences that Motorcraft coils work the best and if $$ and conditions permit try to stay with OEM parts.