just oil your filter yourself, get a paintbrush and spread some engine oil all over it, knead it in then let it stand a while, then squeeze out any excess and fit (do not wring it, it may tear if you do), I am a bit unsure about your airbox picture I can see a square swing arm (mk2)yet the airbox looks like a mk1, somehow the back of the airbox (left of the picture) looks a little unclear?
I will have to guess that the original 160 jet was correct, I would re-fit that one for now, what jet size is in now...did you say...did i miss that?
anywaywere getting sidetracked here talking about main jet sizes, main jet size isnt causing your issue with engine racing and dying with the choke off
do the oiling and exhaust gasket and air leak checks for now Sam