i don't think a kit exists for the 5th gen 4runner
and i get the desire, my background is agricultural and environmental engineering, but if you are talking land replacement it's food vs fuel or if you are talking separate land it has a greater footprint than oil, so basically no one wins except the corn lobby (which is why e85 is a thing). if cellulosic sources become more economical/popular (my undergrad did a lot wof research into sweet sorghum) it will become a better option, but for now corn is king.