I have a 04 WR450F with all the free mods (throttle stop, gray wire, uncorked, snorkel pulled). When I open the throttle quickly the bike acts as if I had hit the kill button. The bike would die without a sputter if I were to keep the throttle open but if I let off the throttle a bit the bike snaps back to life as if nothing had ever happened. I have tinker with jetting enough to think that the problem cannot be solved with jetting alone. I have adjusted my accelerator pump timing to speck and to both extremes without solving the problem. I have removed the carb and inspected the accel pump finding no obvious problems. I have used several different exhaust arrangements (stock corked and uncorked, big gun signature series) and it seems to me that the more open the exhaust is the worse the problem becomes (ie if I put the cork back in the problem goes away and the problem is worst with the big gun). What the heck is going on? More importantly, how do I fix it?