Can anyone tell me off hand where the vac line coming straight down from the back of the throttle body(firewall side) to a metal hardline ~4" toward firewall and toward driver side under throttle cable goes? It's difficult to see without a mirror or removing the tb and I think it gets routed directly to the rats nest, but disappears underneath it so I'm not sure which solenoid it goes to either... This particular short section continuously seems to degrade(soften and loosen) within a few months. Trying to determine why?