I had your exact same problem when I tried a transbrake.I run a stock 9375 Dominator.Went up and down in squirters,different pump cams,etc. all to no avail.Threw my dynomax bullets on while trying in the garage.That helped some,but what really fixed it was a 'shear' plate,a tapered (7 degree,I think)spacer that goes under the carb.It's designed to boost the signal to the carb and help the motor pull fuel.Not saying this is your problem but it could be worth a try.Good luck.