2002 Mazda B2300 ignition timing issues

So I have had an ignition issue for a long time. I have a problem with pre-ignition between 2500-3000 rpm in any gear and have had hard start issues and some hesitating while accelerating. I have new plugs wires, a throttle position sensor. The tps took care of the hesitating and jerky responses and hard starting I had an engine vac performed at a dealer to help remove carbon buldup wich did nothing and after looking down the cylinder through the spark plug hole I can see lots of carbon buildup, wich makes sense for the pre-ignition problem. A friend/mechanic told me about seafoam and said he had a lot of success so I tried pouring some down the spark plug holes and through a vacuum line(while running) and let sit overnight. Started the truck the next day, with plugs in of course, and saw a tonne of smoke and a tonne more on the drive to work out of the system. After the treatment I noticed my throttle response was amazing and much more power, smoother idle and acceleration but still pinging on acceleration only between 2500-3000 rpm and it is much worse if running 87 octane fuel. I have to run 94 octane to almost get rid of pinging. I also have 2 other friends with same truck around same year with same problem.

I am not sure if this is a fault with the advance curve? Or maybe my fuel pump is a little lean when the pedal is to the metal. Maybe I can reset my ecu? The engine has no codes and I tested my cylinder pressure at 173 psi in all 4 cyl? I am at a loss and since I drive 50,000 km's a year I would like to solve this problem. Oh yeah I also replaced both o2 sensors. Thank-you