I think we have a similar problem. My trucks an 06 with 76,000 miles and just died today. I posted my question in engine 911. Just wondering if you ever found the problem? After reading your post it seems that the heat might have something to do with mine too. I lost power for about 30 seconds last week while driving around town. (It was in the high 90's) I had to coast at idle speed through and intersection, no response when I stepped on the accelerator and then all of a sudden power restored. I was really low on fuel and i thought maybe i sucked up some gunk. Now today (temps in the high 90's again) she died completely, still won't start after an hour of sitting. Wish I had an answer, hoping you had luck with yours!