I've had the same problem, though with my truck it seems to have some sort of high-altitude/been wheeling all day vapor lock type issues. If I stop and open the gas cap, it wooshes for about 10 minutes, and then the power seems better again. Imogene from the Telluride side is defintely one of the places I notice it. I also starting getting a gas smell from the pressure release do hicky by the right rear tire. Never been able to diagnose it. I don't know if having a gas tank skid makes the gas tank enough hotter to be an issue.