Limp mode with AC on?

[Mangler]

I have a new problem, and I hope you can help direct me where to start. I was towing an 8000lb (ish) boat over a short grade this summer (hwy 92 from Half Moon Bay CA to 280). Relatively short climb, and I had to drop to 2nd gear to not push the truck too hard and to prevent a high pitch sound I had never heard before (guessing turbo). The problem was not the climb-performance was standard besides the new sound. I made it over the top, and ran low speeds down to the bottom. As I began to accelerate from the bottom I felt like it was in limp mode. No power. I was loosing speed fast. I started looking for a spot to pull over, when I took a shot at turning off the AC, then the power came back. What?? After a long day on the water I was ready to gamble to make it home. I made the rest of the 40 min trip without a problem. I haven't towed that boat since, and I am hoping to finally make it back out on the water in a few weeks. Anyone had an idea what might have happened? I drive the truck every day, towed a smaller boat at least 3 times since on long grades with AC and no issues. I just don't want to take the family out and have a problem with the truck. Any ideas would be appreciated!

 

[cerberusiam]

Check for the AC clutch activation wire scuffing on a metal line and shorting out, that will cause all manner of strange issues.