Try first the following:

1. Clean the MAF sensor with electric contact cleaner;
2. Replace your spark plugs
3. Load up at another gas station (you may be getting bad fuel)

I use Caltex Silver now on my Altis and we don't have engine knock issues unless i short shift and release the clutch abruptly (to starve the a/f mix)... It was the same when we used Shell unleaded on a Vios 1.3, no knock issues. Our other Altis uses LPG (100+ octane) and it never has engine knock.