Also if I tow at 70 or well even drive at 70 with overdrive on it red lines. Is it maybe not shifting into the last gear?

I have a new fuel filter in my truck. I know how to just haven't had a chance to try

Air filters clean. Also ivr noticed it seems sluggish compared to other diesels ive driven. Doesn't have very much power and has a hard time getting over 65 when towning my small fishing boat

No smoke from exhaust. No misfires. What do you mean do I gain oil? At idle I do notice it makes a weird noise. Almost like it struggling for air but then back and it does it like every 15 seconds

Divifing miles by gallons. If I go 60 I get 12mpg

Had it about a month always been like this. Auto tranny w/ overdrive. Normal tired and yes empty no load. It is a dually

I have a 99 f350 with a 7.3. Driving on thr interstate at 71mph 2250rpm I get 8 mpg.....is that normal? I have 4x4 truck has 110k on it