Did you do a "Throttle Reset", mine ran good then bad, rough on and off until I did the throttle reset. You could also have a TB gasket leak. Also check the line that is kind of large rubber hose and has a two into one that is on top of the TB I think. It can come loose if not pushed all the way down on the connection point. I have the 74mm TB but not the bigger MAF. I think if I change the MAF I would need a different Air box to get any good out of it.