When you are attacking your opponent with a godsword, your opponent can eat 2 pieces of food between your 2 hits. Thanks of the saradomin brew, you can eat 2 pieces of food + drinking 1 sara brew which restores in total 63 hp. That's way too much and it fucks up pking, because every time you want to use your special attack with a godsword when using by example a whip, he can eat 1 piece of food + drinking 1 sara brew which restores 40 hp...
I don't know if it's made so, but I think it can't be the meaning of that. You have to set a timer between eating a piece of food and drinking a potion, because there isn't one now and their should be one, because potions can heal also like food ( and their is a timer between eating food ).

There is also a timer between drinking potions. This is all intended. You should try to combine and time your special attacks with vengeance and poison, you'll get way more success that way. This isn't a bug.