No performance problems. the only thing......I think....would be that whenever you are on the highway and let the gas pedal off, the IAC opens up to let some air in so it won't stall, but if you opened the TB plate I guess it should go back to 1000 rpms where you set it, and gas mileage? I don't know........... The computer opens up the IAC a little more when you turn AC on or when you put it in gear(AUTOMATIC).