Injector O rings
 

I have a question. I have replaced the fuel injector holders and the seals, I also ordered the O-rings but for the life of me I can not tell where they are installed at. When I changed the holders and the seals from the original injectors (that's all that was there:confused: ) there were no O-rings to be replaced. My question is, even though there are seals do the O-rings still get installed or does the seals act as both. Could the lack of an O-ring be part of my problem for roughness at idle?

I also installed new injectors..