Good or decent tuner box for 2006 Ram 3500 4x4 daily driver?

My 2006 Ram 3500 4x4 has right at 144,000 miles I on it now, I have kept track of the fuel mileage since new and have seen a steady decrease in it for the last 30,000 miles
I had one injector replaced several years ago and do not know what the normal life span is on them, what is a good number to use to replace them
I've heard that upping the power through the use of a tuner box will help reduce the fuel consumption, true or not
If this is so what is the best box to use?
I drive the truck empty around 99.0 % of the time, I do use it to pull my 24 Ft enclose Pace car trailer with drag race cars in it., the last time I weigh the trailer with my old pump gas Duster in it it weighed right at 8600 Lbs. on the axles. .The new S/P car weighs right at 700 lbs. less
I do have a cab even camper shell on it also, the best mileage I've seen towing the trailer was around 14 MPG.
Empty it use to get a little above 20 MPG, on the last long trip empty I got right at 17.4 MPG
All comments and help are welcome

My advice? Leave it alone as I got 561xxx out of mine which was never touched.

I have 265K on my 2003 CTD and changed the injectors when it got hard to start, which was around 210,000. I also added FASS filters to make the new injectors (hopefully) last longer. I use the Edge tuner because my truck didn't have gauges so I needed gauges in my tuner.

I have a TST PowerMax on my '04 DR DRW. 315,000 miles worth. It's night and day between stock, you can set it at zero and the truck is basically stock as it's not true bypass because of the boost. This one doesn't increase the rail pressure like the other programmer boxes. This thing has separate torque and HP settings zero to 9. It will eat the stock converter if grunted too hard.

I'm assuming you have a Cummins in that truck. If so, I went with an EFI LIVE download, I chose a towing tune, 5 stage, 15 to 185 HP. I have seen an uptick in fuel economy and definitely more power. I haven't used stage 5 yet because my transmission is still good!