27 on the highway sounds a bit high, I can get 22-23 on the highway, and I feel I'm doing damn good.
Check your sway bar links and bushings, even a slight movement is enough to make that noise on our trucks. Swap bar shouldn't be able to move at all. 93k it wouldn't hurt to replace them anyways as preventive maint. I believe this will solve your problem. It did on mine.