[eggsuckindog]

Be somewhat careful running too much WOT without the air box - tends to lean everything out. I don't think its the fuel pump personally, might be one of the carbs as Denny mentioned. This might be a something to try if you do pull the air box - put a finger over a small part of each carb - just a little - that would tend to richen that carb up a bit and see what happens. I would lean towards some coil breakdown or something ignition related though.