SFM, I don't mean to scare you with this... The 3rd gen engines are know to drop a valve seat out of the head and hold valves down enough to contact the piston. If one was way off, you may want to look deeper into that cylinder.

 

thanks i will have to look into it soon.

 

Normal mileage on summer fuel, roadtrip driving is 18-19mpg in my '07. Drops about 1mpg on winter fuel. Overall, drops about another 1mpg with normal grocery getter duties, mixed hiway and in town. All hand calc. Overhead is only high by 0.5 to 1mpg. This is all 75-85mph highway driving.
For some reason, my truck gets better mileage at high altitude with the up and down the passes averaging out I guess, than it does at low altitude flatland. Was only getting 16-17 mpg on a trip to WI from CO last winter, where I get 17-18mpg in winter up at altitude, say from Vail to Grand Junction and back.....weird.
I've enver found a light enough egg to place under my shoe to get much over 20mpg. Got 20-21 mpg a couple times in this truck and my 02 DMax driving strictly county/state highways, 55-65mph.