Based on the weight and size of the trailer, that truck shouldn‘t even know it is behind it. If it is a really steep hill, maybe. Just a thought, sounds like it may be lacking fuel or air under load. Based on what you have replaced I am assuming you already have checked that, but on my diesel that is what I feel when the fuel filter is getting old. many other things can cause lack of power but a flat cam can act like it is running great but has no power.
He never said there is a lack of power. He says it uses 3rd gear. It is a 5spd trans. It is gonna use 3rd gear
And 11mpg in a 3rd Gen 2500 with a Hemi....that is pretty good.
3rd gear is the same as the 8spd using 5th.
Guys with the 1500 5th Gen RAM are not getting getting much more than 11 mpg empty grocery getting.
As you can see in my pics my 2015 is getting 11.7. That is because I have been "trying to get more" it involves alot of coasting. usually in the winter you will be lucky to see 9 with my short commute and band practice pickups, quick trips to the grocery store
And I am pretty sure my 03 actually says 6.75 mpg right now on it's evic. As we do not drive it much.
11 mpg and 3rd gear are pretty normal.
If everything was replaced and he got a head of steam for the hill...he should lock out OD when towing and might see 11.5 and maybe 4th for a bit.
I do not think he has an issue. Given what he has told us.
He needs a smaller vehicle or a transmission with more gears...which still will be the same but different.
We just took a trip in our Cherokee. 9 speed auto. Up through the hills in PA on Route 36. I bet it never saw 9 th. Rarely if ever in 8th. Maybe 7th going down hill. I bet the majority of the trip it was in 5th 4th and 3rd. Some hills...even 2nd