A portion of the threading in the intake manifold (at the TB) stripped out. I believe it was caused by using replacement bolts that were too short, ie holding the TB elbow and TB onto the mani by just a few threads, which were under too much pressure, causing them to give out. I replaced them with longer bolts all around and they all stayed tight; however, it still eventually leaks under boost leak testing between the TB and elbow. I'd like to get a completely redone TB from throttlebodys.com eventually, so I'm holding out for that to replace the gasket I think.