Took it to the dealer yet again. Here's what I've gathered....the truck has an "econodyne" tune. When I asked them to tune it to "maxidyne" the lead tech said it probably wouldn't make much difference. But they've been playing with this truck for so long that even they want to figure out what's going on with the truck, so the tech went for a ride along with me. I had a 48' flatbed with about 5,000lbs loaded on the deck (essentially empty) got on the highway and right away he noticed that the truck was incredibly slow. His computer was telling him that the truck was only putting out 67% power and wouldn't hit anything over 1300 lb-ft pounds of torque at wide open throttle pushing about 25psi. Drove around with him for 45 mins up and down hills, highway, back roads, the works.
Got back to the dealership and he updated the software on the truck. He also pulled up the programming and told me the "econodyne" tune has 4 settings, 0-1-2-3. The truck was set at 2, so he changed it to 0. He said "it probably wont fix the issue, but try it and let me know either way". So I left the dealer and as soon as I got on the highway, i noticed a significant difference. I was able to pull much harder on inclines and the boost gauge was getting up to 40psi at full throttle, even the throttle response was significantly different.
Here's my problem, I'm still having a hard time up the hills with 20,000 lb loads, and I truly feel it's a tuning issue, but they keep telling me they'd hate to have me spend the $3,000+ to re-tune the truck because they dont think it would change much. We pull upwards of 100,000lbs consistently, and I'm afraid this truck isn't going to handle that kind of weight... thoughts?