ok i bought an autometer Air/Fuel gauge for like 15 dollars that had never been used. anyway i wasn't planning on buying one of these cause i know there kinda usless but i figured if i could get it for just that might as well. anyway i tried to install it and i could never get it to work and i'm prety sure all my connections were good but still never got it to work. anyway i'm not gonna use it anyway not but when i started my car while i had it in and after i took it out it would start up normal and then idle really low and even when you come to a stop it has a real low idle. but if you let it sit for a little while it will get back up to normal. any ideas on what might cause this? thanks guys.

1997 Mitsubishi Eclipse GSX: K&N Filter, John Sheppard built transmission with GVR4 1st gear, autometer boost gauge, "free mods", Greddy type-s BOV, broken shifter