I'd go find any bio that you can and fill a fresh fuel filter with it, and fill as much of the tank with it as well. Bio is better than any additive.
Damn is it knockin again too?
Just a passing retarted thought i had while driving home tonight and i dont remember all the specifics of your problem but could it possibly be a severly lifted cup causing the low compression and making it smoke by letting coolant into the chamber??? Im sure im way off and i cant come up with a reason that a lifted cup would make it knock but it was just a passing thought.