Towing Woes...Again! LONG!

[klaybus]

Truck Specs

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1999 Dodge RAM 215 HP Cummins
DTT Auto
4.10 gears
STOCK 265 tires
F1 Mach 1.2s (80 hp plus or minus)
PDR 35\12
Edge EZ (set to low setting)
AFE PG7
Rips 4" exhaust
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Just returned from our annual houseboat trip to Lake Roosevelt. Two weeks ago I pulled our #8500 5vr over to Blue Lake via I-90 & it pulled ok. When I hit Vantage I had to take it out of OD but other than that it seemed to pull fine. I returned home empty that night & last Thursday we headed back over to Blue Lake for the night with our 19' boat in tow. Again, pretty much uneventful.
For those of you who aren't familiar with the NE Washington area it's HOT this time of year with many long, winding hills. Friday we left Blue Lake & headed for Lake Roosevelt with our boat in tow. Again, not really any issues at all. After our houseboat trip we ended up having to drive to Kettle Falls to replace my mother in laws batterys in her coach....Anyhow, thats where this begins...Sort of.
While pulling on this winding hilly roads I would have to come in & out of OD to keep my egts in check at around 1150. No real biggy but a little annoying. We made the 60 mile jaunt one way took care of my mother in law & headed back to Blue Lake.
I guess here's where my problems began!
We left Blue Lake yesterday afternoon around 2pm in 100* weather with our #8500 5vr in tow. Those familiar with this area know of the HUGE hill going around Park Lake headed to Hwy 2. We pulled that in drive (no OD) with 190*+ water temps & 1100*-1150* at about 50 mph. I wasn't too disappointed considering the hill & my weight. (combiined about 16,000 lbs)
When we reached hwy 2 & turned left (West) we immediately hit a long winding grade which I could only reach 50 mph max trying to keep my pyro in the 1150*-1200* range. Water temps went to about 210* & then started to plummet back to 190* when the fan engaged as we crested the top. This was the first of many typical experiences until we got down to hwy 97 where it stayed realitively flat with slight grades.
Everything was realitively uneventful after this until we hit Washington Pass on hwy 20....THIS is where I was TOTALLY disappointed im my trucks performance!
For those that have traveled this pass, you know what it's like. Two long inclines & then you hit the WALL! On the inclines my truck started falling on it's face. In drive I couldn't keep the RPMs up & keep the EGTs at 1200*! I hit 1400* a few times & my water temps shot to close to 220* so I pulled over, HIGH idled the engine with the fan engaged until my water temps got back down to 190*. About this time the trans temps were at 200* too so I shut her down for a few & tried to think about my options.
First I unplugged my EZ which I had set prior to the trip on the lowest setting & I then tried to go again. I got to the bottom of the wall & again, EGTS were at 1200*+ & climbing, water at over 200* & virtually just didn't have the power! At this point I just said F--K it! I put the truck in 4WD, engaged Bob V's 2-low & was able to pull the pass in lock up, OD at about 25-30 mph! Thank GOD for Bob V's 2-low kit. It saved the trip...

Now, fella's....WTF?!?! Several years ago I had the same problem trying to pull Waterville hill outside of Wenatchee but my setup was quite different. Back then I was running this.

1999 Dodge RAM 215 HP Cummins
DTT Auto
DD II's
Stock HX-35\12
285's tires
EZ (high setting)
3.54 gears
AFE PG7
Rips 4" exhaust


Now.....

1999 Dodge RAM 215 HP Cummins
DTT Auto
4.10 gears
STOCK 265 tires
F1 Mach 1.2s (80 hp plus or minus)
PDR 35\12
Edge EZ (set to low setting)
AFE PG7
Rips 4" exhaust

Am I asking too much of this truck? I should note my 60 yr old mother in law in their 96 Ford 460 1-ton auto 2wd dually pulled this pass starting at the bottom from a dead stop with a 11'-6" camper was able to crest the top of the pass at 55 mph!

Again, do you guys think I'm expecting too much of my truck? I've changed my ring & pinions from 3.5s to 4.10s, got rid of the DD IIs for F1 1.2s, changed to a PDR 35 from the stock HX-35....I'm at a loss at how lousy this truck performs when I really need it to step up! I'm assuming a 14 cm WG housing would help at cruising rpms but I don't think that would have helped that significantly when I hit the wall trying to pull Washington Pass & I think it might have even hindered it more with laggier spool up.

PLEASE send me your suggestions. All I can figure is a stick over an auto so I have the gear choices to keep the rpms high......

Clay