New member here, I know this topic has been beat to death but i kinda have some unique problems. I have an idle surge going from 1-2krpm. it'll go away if i restart the car most of the time but it comes back after driving. I just got the car and am still figuring out the stupid things the guy before me did. It's a swapped h22a4 completely stock besides a 1320 header, full exhaust, and an ebay intake. at first i was thinking iacv as that's usually the culprit but i noticed the post o2 sensor has the wires pulled out of it. and then realized theres not even a pre o2 sensor bung. do these headers come like this, and you have to weld a pre bung in? i'm wanting to get the o2 stuff figured out before i go to replacing the iacv as they're kinda expensive for a used piece of aluminum lol. there's also like 5 different plugs not plugged into anything. but everything seems to be plugged into the engine and harness. so i have to tackle that too. Would my best move be to weld a pre sensor bung in and replace both sensors? and if anyone has a link to an engine bay harness wiring diagram that would be cool. thanks