the biss has a small o ring fitted on it, from what you described it will stay loose until you replace this, if you tightened it all the way you already fucked up the idle, if you would have to keep on the gas while idling that just might mean that the idle speed control soleniod is fucked up, and for your dsm, buy a haynes manual and sit down and read chapter 6 i believe, it is all on diagnostics and has all the codes and troubleshooting solutions, and if you think you have a bad injector, pull the spark plugs it will tell you right away. Are you sure that tech school of yours isnt for the "special" kids?