I don't think it's an EGT issue. When I had a chance to peek at my cylinders and pistons; they were in amazingly good shape, and I've seen some high EGTs with my truck.
I still think it has to be a fuel issue, with EGT that low you're not fueling hard enough. Usually with good fueling your water temps will climb to 200* as well. Shoot I bet even with a set of BD twins a truck would see around 1500* with a similar fueling setup as you have...