Adman,
I have nearly the same set up as you, except shortbed. (2003 Ram 2500 QC/Shortbed, 4x4 Laramie with the 545RFE transmission and 3.73 axle ratio) all stock and experience what I consider poor towing performance as well - yet not near as bad as what you detailed.
Like your's, I consider mine pretty tip top. Currently has just under 87,000 miles on it.
I used to have a 24' Haulmark carhauler that weighed in at about 8,500 fully loaded (sold due to weight) and have since owned a 22' toyhauler (probably about 6,500 loaded) and now a 30' 5th wheel (about 6,500 loaded). While the 5th wheel tows the best due to being a 5th wheel, it isn't all that much better than the heavy carhauler (however that had a lower profile than the 5th wheel and I had a shell on the truck).
The 3.73 gears with the Hemi and 545RFE transmission makes no sense to me for a heavy duty truck, especially the Laramie. I gotta think most 2500 Laramie's are purchased to tow RVs - not to put a contractor/utility bed on.
I ran into this thread while researching a tuner/programmer, but not sure I want to go that route but am still considering it if for nothing else to know transmission temp. I've also considered changing the axle ratio, but Dodge want's $2000 per axle. I'm sure a transmission shop would be less, but still expensive.
Thanks for the all the info in this thread, I'll try premium fuel for towing and not freak out when the Hemi winds itself up to get into its powerband. Regarding higher octane fuel, I guess I though I heard/read once you start using premium fuel you should always use it (although my truck isn't my daily vehicle, so it wouldn't matter much).
