leaky injectors on tbi

ok...i have a problem...i can not get the fuel injectors on my 3.9tbi ram to seal.....i have tried everything to no avail. i have replaced all o-rings and gaskets but cannot get a tight fit on the injector and fuel poors out of it....is this a common problem. do these units just create too much slack over time...will i have to replace my injectors??? i have even tried different size o-rings to make work but still dumping fuel...i even tried a different tb and it had the same problem with one of them...i also noticed that the spacer was missing on my new tb that i got of ebay. i believed someone torked down on the black caps on top of the injector to push the whole injector too far in the hole and buggered it all up cause when i got it it was sitting all ka-ka'd i am about to throw a carb on this stupid thing....i can't wait until i get my motor for this truck!!!