I was having a misfire. So i changed all my vacuum lines,intake gasket, plugs and wires. Ran worse than it did before.Then i found all my coil packs were cracked. Start up great when i replaced that. Drove down the road great but it idled horrible. Checked for leaks could find anything. So i started unhooking lines to see if anything made a difference. What i found if i unhook that line in the picture it idles prefect. Does anyone know what that is?