Ok, here's the low down on why the VE throttle body screws are coming loose. You can't blame it all on the screws. In fact, they are the same screws used in most Nissan's throttle bodies. Most of the blame lies with the VE throttle shaft(black shaft you see in pics). The shaft is made out of a metal graphite matrix making it brittle and prone to cracking. It also has a different heat expansion rate than the metal screws. Over time and many heat cycles, the screws work themselves loose.
Solutions:
1. Locktite or JB weld(making it permenant) the screws.
2. Get a DE throttle body(without the black throttle shaft) and call it a day.
I prefer the second. With solution number one, by taking the screws off and on, you run the risk of further damaging the brittle/fragile throttle shaft.