Heavy Detonation STILL?



So I thought I had this beat.

But tonight coming off the highway I had to floor it at the light and she was pinging very hard.

The car was a little warm 220 degrees, when I shut off the heater it goes from 195 to 220 degrees?

I also put in a tank of 93 octane last night. I do that about once every other month or so. I usually run 91 octane I did not think it would make much difference.

I am convinced I have an issue with the Vac advance, that is why I posted the previous topic.
I am getting a Dial Back light in about 30 minutes and I will check everything again tomorrow.

But I also have a carbon problem, this engine has been spitting carbon out the tail pipe as long as I've owned the car. It has even created a nice spray pattern on the driveway. There is so much crap shooting out of there every time the car wams up. And the plugs are constantly coming out black and fouled. I am building a replacement engine and only need to make this one run for about six more months. So I am open to suggestions on how to fix this. Or what might be causing this other than all of the above, I am trying to narrow this down.

Any help would be appreciated. I am going to give this one more shot then I am taking it in to a mechanic.
Jimbo, Here is an old trick for de-carboning an engine......Start the car & have a buddy rev it up to about 2000 rpm's. SLOWLY pour 10-12 ounces of water down the carb......pour slowly so as not to kill the motor.....This is best done outside because the carbon makes a big mess on garage walls & floors.....ask me how I know ;)

Same thing but I used to use an old spray bottle that I washed out. Does the same thing. I have trickeled water in, like he said just go easy.