Better late than never.
I had same problem:
Mine started with some light pinging, then over time (6 months) it got worse, then I was getting no power above 2500 rpm.
91 octane plus octane boost made little difference.
After these changes, I now use 87 octane with no pinging and tons of power.
1) I took apart the MAF sensor (you'll need torx security screw sockets), I sprayed the entire inside with CRC MAF cleaner. Especially the little resistors? In the MAF sensor. Make sure you don't touch them with the spray tube, they look very delicate. I sprayed the little resistors from both sides of the MAF body then let dry. I always kept the spray tube several inches away from the little resistors.
2) I cleaned the electrical connections (2 of them), one at the MAF sensor and one mounted on the inner fender. There was some white oxide? On the connections.
3) Then I checked the air temp sensor? Just downstream of the MAF sensor and the wire in the center was touching or almost touching the inside of the sensor body. Could of been grounding out? I carefully moved it to the center of the sensor body.
The next day I drove it and I had all my power back plus 2 mpg
Anyway, all is good now.
Sunday, January 1st, 2017 AT 10:03 PM