Hi, I have not followed what has occured to your car before this thread, but I have had problems every summer when ambient temp is high. Especially in stop and go traffic, the car turned into limp mode. I have got lots of advice through this forum, but never really believed any of them as the cure. (Eventhough they have been of great help to make me understand my car in general and for future problems).
Some weeks ago when the car turned into limp mode I discovered that if I used the cruise control it worked again! Which in my mind rolled out most of the suspects and I took some WD40 (?) and sprayed the gas linkage. Since then the car has worked fine!
I cross my fingers that it was the cure, and in any case, try if the CC will help your car out of the limp mode and you are in a more narrow range to search for the problem...