Remove your injectors two at a time and crank the engine.See if the
injectors spray gas like a cows utter squirts milk. A single 10mm bolt
holds the injector set to  each bank.They then wiggle out easily. New o-
rings can be had at advance auto parts.These o-rings are a vacuum leak
area, so it is good to replace them. Got to order them(two days).About
$3.I know a list vender that will take a week or two to get them to you.