boggling problem?

i have a 1zz, with a ame cai on it, when its idleing and you rev the motor slightly it boggles as if its going to stall but doesnt, it will continue unless you get the rev higher than 35-40000 rpms, and sometimes when i go to launch quickly it again wil boggle out until the rpms get up past 4 again.. im not sure if it has anything to do with the intake? or if it has something to do with the fuel because sometimes even befor i added the intake it would do the same.. so i was thinking about changing the fuel filter or even maybe the pump? or doing something diffrent with the intake setup? any suggestion? or if anyone has had this problem befor and solved it could help? thanks