what causes it?
 

can some1 tell me what causes fuel cutoff?

boost leaks
turning up the boost too much

if you turn the boost right up and try to go past fuel cut the car will blow up as the ecu can't deliver enough fuel

fuel cut is there for a very good reason
learn about your engine and the way it works before boosting it up

whats hte best way to defend against the much dreaded fuel cut

add more money

btw an N/A will never hit FCO