Did you check plugs to make sure they are ok? I know they are a PITA, but simple engine diagnostics (from when I was little) I pulled those to make sure gap was good and you then could see if they were fouled - telling you if there were other issues....

Did someone else ask if brakes are sticking? Had that happen once and dropped mpg pretty good... I know you said it happend 4 mo ago so snow isnt your issue (or is it) but snow stuck against under carriage stuff - like parking brake ext can also cause a drag. Thsi usually happens with LOTS of snow or continous driving in wet at or below freezing...

 

Thanks guys for all the info! I have had the MAF sensor checked along with the brakes and e-brake aswell by the dealership and they are convinced the bakes are good and not binding up at all. The reason I run the better fuel is because I'm planning on adding a SuperChips programmer just havent got around to it yet. I need to check the spark plugs I've been thinking thats a valid point but the boys at the dealership say no way! with only(60,000)miles.

 

Pass on the SuperChips junk. Get a Edge/Gryphon/SCT tuner.

 

My mpg's started dropping off about a month ago, nothing drastic but still they dropped and kept dropping until the truck was noticeably missing at cruising speeds. Since there was never any codes or idiot lights I checked and cleaned everything that has already been mentioned, ended up being 5 plugs failed that had to be replaced.

 

Its still possible to have plug problems with 60,000 miles. I would personally take off and clean the throttle body and MAF sensor, and replace all the plugs. Your mileage is going to drop a bit with winter blend gas but shouldnt be a huge amount.

 

I recently went through this with my 06. Mileage seemed to be down so I checked everything out. Could not find anything wrong, truck was running like a top!

My IWE actuators were stuck on. I was in two wheel drive but the actuators had stuck in the engaged position ever since the temps had fallen below freezing here. I jacked the truck up and started it and with the 4wd selector in the 2wd position the axle would turn with the wheel. After the truck was in the garage for the whole night in warm temps, the actuators loosened up enough and when I started it up and spun the wheel, the axles did not move.

I checked my vacum on both sides and it read 19 on my old vacum gauge. With that reading I figured the solenoid was working ok. With the truck running I pulled the hose off the IWE and the axle would turn with the wheel. When I hooked the hose back on, then the axle stayed still when I turned the wheel. After reading all the IWE threads on here I figure my IWE's are just on the brink of going south and I am lucky they stuck on and did not partially engage. Could explain my loss of mpg along with the winter gas. Sorry for the long post.

 

i would def check the plugs ford recommends them every 60k on the 5.4 i did mine at 55k