The cooler the engine runs, the less likely it will detonate. I have the same problem still. Here is what I have found.
I replaced spark plugs, wires, cap, rotor, fuel filter, ECT, IAT. The vacuum gauge reads normal. My car runs inbetween the N and the O in "normal". I have ran "combustion chamber cleaner" through the vacuum lines.
Nothing has helped. Absolutely no changes.
I still need to hook up a fuel pressure gauge (to test fuel pump & regulator). That is my last hope. If the pressure is normal, I will think about taking it to a shop. Maybe the PIP module? Coil? That is about it! My MAF was replaced about a year ago (before I got the car, they installed a K & N filter, and the oil clogged the MAF sensor, so they replaced the MAF), so I ruled that out of the equation. But that may still be the problem.
Hook up a vacuum gauge and see what you read. I can't remember what mine read (19-25 psi????). But it was within spec (according to the haynes manual). It was also steady. Didn't fluctuate at all. If the vacuum drops suddenly, then goes back to normal, and so on, one of your cylinders is bad. If it does, PM me and I will tell you how to figure out which one is bad.
Hope this helps!
Scott