I have a 1997 mustang GT, just bought a 75mm plenum from accufab and bolted it on and car ran fine. it was new in box. bought a used with 800 miles on it 75mm accufab TB guy said it was cleaned and ran fine when he pulled it off. with the accufab plenum and stock TB car ran good just had a compression sound in motor when i turned it off. when I added the accufab TB it 's idle was 1300 or so RPMs until I gave it gas and it was jump up to 2300-3k RPMs and want idle back down. Im also using a stock mass air meter and a BBk cold air kit with fender K&N filter. when I emailed the guy he said his tech guy told him it was getting to much fuel for the computer to compensate for it and causing it to idle high, and that I just needed a tune up. the accufab TB came with a throttle position censor already on it looks new. anyway does anyone have any idea's I was trying to get it running good for a carshow in my area by sat. any help would be appreciated.