Ok, so I'm pretty sure I have a vacuum leak, because the engine does not idle properly, the revs bounce up and down a bit, the car occasionally stalls, and it sort of sounds like its missing. Sometimes when I blip the throttle, I'll get some black smoke out the rear, and snow under the exhaust pipe turns sort of black. Also, I can hear a sucking from the passenger side of the intake manifold when the engine is idling. When you rev the engine and then let the RPMs fall, the sucking goes away.
I ran a vacuum test, and at idle (or at 500 RPMs where the car mostly idles) I'm only getting something like 7 inches of vacuum. When I rev the engine, the vacuum goes up to maybe 15 or 17 inches.
I don't get any codes when running the KOEO test, but when I run the KOER test I get codes 172 (HEGO (HO2S) sensor fault lean) and 136 (HEGO (HO2S) sensor fault, always lean).
When I run the cylinder balance test, I get 010, which indicates a problem with Cylinder #1.
I plan on removing the intakes, cleaning them, and replacing the gaskets, as well as all the injector o-rings.
Does everything here point to a vacuum leak of the intake manifold, or is there something else that I should be looking for at the same time?
